MaxAdmin - Admin Interface

Looking for the latest MaxScale documentation? You can find it here: MaxScale 2.2

MaxAdmin - Admin Interface

The Maxscale Administrative & Monitoring Client Application

Overview

MaxAdmin is a simple client interface that can be used to interact with the MariaDB MaxScale server, it allows the display of internal MariaDB MaxScale statistics, status and control of MariaDB MaxScale operations.

MaxAdmin supports

  • Interactive user sessions

  • Execution of one-off commands via command line arguments

  • Execution of command scripts

Configuring MariaDB MaxScale for MaxAdmin

In order to be able to use MaxAdmin, MariaDB MaxScale must be configured for it.

There are two ways MaxAdmin can connect to to MaxScale.

  • Using a Unix domain socket.
  • Using a hostname and port.

The first alternative is introduced in MaxScale 2.0 and is the secure and recommended way. The second alternative is available for backward compatibility, but is insecure and deprecated and will be removed in a future version of MaxScale.

An example configuration looks as follows:

[MaxAdmin]
type=service
router=cli

[MaxAdmin Unix Listener]
type=listener
service=MaxAdmin
protocol=maxscaled
socket=default

[MaxAdmin Inet Listener]
type=listener
service=MaxAdmin
protocol=maxscaled
address=localhost
port=6603

In the configuration above, two listeners are created; one listening on the default Unix domain socket and one listening on the default port.

Which approach is used has other implications than just how the communication between MaxAdmin and MariaDB MaxScale is handled. In the former case, the authorization is based upon the Linux identity and in the latter case on explicitly created user accounts that have no relationship to the Linux accounts.

Note that if the socket path or port are changed, then MaxAdmin has to be invoked with -S or -P respectively.

Running MaxAdmin

Depending on whether MariaDB MaxScale has been configured to use Unix domain sockets or internet sockets, MaxAdmin needs to be invoked slightly differently.

If Unix domain sockets are used, then MaxAdmin needs no additional arguments:

alice@host$ maxadmin
MaxAdmin>

The above implies that the Linux user alice has been enabled to use MaxAdmin.

If internet sockets are used, then either the host, port, user or password has to be specified explicitly:

alice@host$ maxadmin -u maxscale-admin
Password:
MaxScale>

When internet sockets are enabled, initially it is possible to connect using the username admin and the password mariadb. These remain in effect as long as no other users have been created. As soon as the first user is added, the use of admin/mariadb as login credentials is disabled.

If Unix domain sockets are used, then initially only root has access. MaxAdmin usage can subsequently be enabled for other Linux users.

The MaxAdmin client application may be run in two different modes, either as an interactive command shell for executing commands against MariaDB MaxScale or by passing commands on the MaxAdmin command line itself.

Working With Administration Interface Users

What Users Have Been Defined?

In order to see the Linux users for whom MaxAdmin usage has been enabled and any explicitly created accounts, use the command show users.

MaxScale> show users
Enabled Linux accounts (secure)    : alice, bob, cecil
Created network accounts (insecure): maxscale-admin
MaxScale>

Please note that root will not be shown.

Enabling a Linux account

To enable MaxAdmin usage for a particular Linux account, use the command enable account. This command is passed a user name, which should be the same as that of an existing Linux user.

MaxScale> enable account bob

Note that it is not checked that the provided name indeed corresponds to an existing Linux account, so it is possible to enable an account that does not exist yet.

Note also that it is possible to enable a Linux account irrespective of how MaxAdmin has connected to MariaDB MaxScale. That is, the command is not restricted to MaxAdmin users connecting over a Unix domain socket.

Disabling a Linux account

To disable MaxAdmin usage for a particular Linux account, use the command disable account. This command is passed a user name, which should be a Linux user for whom MaxAdmin usage earlier has been enabled.

MaxScale> disable account bob

Note also that it is possible to disable a Linux account irrespective of how MaxAdmin has connected to MariaDB MaxScale. That is, the command is not restricted to MaxAdmin users connecting over a Unix domain socket.

Note that it is possible to disable the current user, but that will only affect the next attempt to use MaxAdmin. root cannot be removed.

Add A New User

To add a new MaxAdmin user to be used when MaxAdmin connects over an internet socket, use the command add user. This command is passed a user name and a password.

MaxScale> add user maxscale-admin secretpwd
User maxscale-admin has been successfully added.
MaxScale>

Note that there is no difference in rights between an enabled Linux account and an explicitly created user.

Delete A User

To remove a user the command remove user is used and it is invoked with the username and password.

MaxScale> remove user maxscale-admin secretpwd
User maxscale-admin has been successfully removed.
MaxScale>

Note that it is possible to remove the current user, but that will only affect the next attempt to use MaxAdmin.

Command Line Switches

The MaxAdmin command accepts a number of options. See the output of maxadmin --help for more details.

Interactive Operation

If no arguments other than the command line switches are passed to MaxAdmin it will enter its interactive mode of operation. Users will be prompted to enter commands with a MaxScale> prompt. The commands themselves are documented in the sections later in this document. A help system is available that will give some minimal details of the commands available.

Command history is available on platforms that support the libedit library. This allows the use of the up and down arrow keys to recall previous commands that have been executed by MaxAdmin. The default edit mode for the history is to emulate the vi commands, the behavior of libedit may however be customized using the .editrc file. To obtain the history of commands that have been executed use the inbuilt history command.

In interactive mode it is possible to execute a set of commands stored in an external file by using the source command. The command takes the argument of a filename which should contain a set of MariaDB MaxScale commands, one per line. These will be executed in the order they appear in the file.

Command Line Operation

MaxAdmin can also be used to execute commands that are passed on the command line, e.g.

-bash-4.1$ maxadmin -S /tmp/maxadmin.sock list services
Password:
Services.
--------------------------+----------------------+--------+---------------
Service Name              | Router Module        | #Users | Total Sessions
--------------------------+----------------------+--------+---------------
Test Service              | readconnroute        |      1 |     1
Split Service             | readwritesplit       |      1 |     1
Filter Service            | readconnroute        |      1 |     1
QLA Service               | readconnroute        |      1 |     1
Debug Service             | debugcli             |      1 |     1
CLI                       | cli                  |      2 |    27
--------------------------+----------------------+--------+---------------
-bash-4.1$

The single command is executed and MaxAdmin then terminates. If the -p option is not given then MaxAdmin will prompt for a password. If a MariaDB MaxScale command requires an argument which contains whitespace, for example a service name, that name should be quoted. The quotes will be preserved and used in the execution of the MariaDB MaxScale command.

-bash-4.1$ maxadmin show service "QLA Service"
    Password:
    Service 0x70c6a0
            Service:                QLA Service
            Router:                 readconnroute (0x7ffff0f7ae60)
            Number of router sessions:      0
            Current no. of router sessions: 0
            Number of queries forwarded:    0
            Started:                Wed Jun 25 10:08:23 2014
            Backend databases
                    127.0.0.1:3309  Protocol: MySQLBackend
                    127.0.0.1:3308  Protocol: MySQLBackend
                    127.0.0.1:3307  Protocol: MySQLBackend
                    127.0.0.1:3306  Protocol: MySQLBackend
            Users data:             0x724340
            Total connections:      1
            Currently connected:    1
    -bash-4.1$

Command files may be executed by either calling MaxAdmin with the name of the file that contains the commands

maxadmin listall.ms

Or by using the #! mechanism to make the command file executable from the shell. To do this add a line at the start of your command file that contains the

! directive with the path of the MaxAdmin executable. Command options may also

be given in this line. For example to create a script file that runs a set of list commands

1
2
3
4
5
6
7
8
#!/usr/bin/maxadmin
list modules
list servers
list services
list listeners
list dcbs
list sessions
list filters

Then simply set this file to have execute permissions and it may be run like any other command in the Linux shell.

The .maxadmin file

MaxAdmin supports a mechanism to set defaults for the command line switches via a file in the home directory of the user. If a file named .maxadmin exists, it will be read and parameters set according to the entries in that file.

This mechanism can be used to provide defaults to the command line options. If a command line option is provided, it will still override the value in the .maxadmin file.

The parameters than can be set are: * 1.4: hostname, port, user and passwd * 2.0.0 and 2.0.1: socket * 2.0.2 onwards: socket, hostname, port, user and passwd (and as synonym password)

An example of a .maxadmin file that will alter the default socket path is:

socket=/somepath/maxadmin.socket

Note that if in 2.0.2 or later, a value for socket as well as any of the internet socket related options, such as hostname, is provided in .maxadmin, then socket takes precedence. In that case, provide at least one internet socket related option on the command line to force MaxAdmin to use an internet socket and thus the internet socket related options from .maxadmin.

The .maxadmin file may be made read only to protect any passwords written to that file.

Getting Help

A help system is available that describes the commands available via the administration interface. To obtain a list of all commands available simply type the command help.

Available commands:
add:
    add user - Add insecure account for using maxadmin over the network
    add server - Add a new server to a service

remove:
    remove user - Remove account for using maxadmin over the network
    remove server - Remove a server from a service or a monitor

create:
    create server - Create a new server
    create listener - Create a new listener for a service
    create monitor - Create a new monitor

destroy:
    destroy server - Destroy a server
    destroy listener - Destroy a listener
    destroy monitor - Destroy a monitor

alter:
    alter server - Alter server parameters
    alter monitor - Alter monitor parameters

set:
    set server - Set the status of a server
    set pollsleep - Set poll sleep period
    set nbpolls - Set non-blocking polls
    set log_throttling - Set the log throttling configuration

clear:
    clear server - Clear server status

disable:
    disable log-priority - Disable a logging priority
    disable sessionlog-priority - [Deprecated] Disable a logging priority for a particular session
    disable root - Disable root access
    disable feedback - Disable MaxScale feedback to notification service
    disable syslog - Disable syslog logging
    disable maxlog - Disable MaxScale logging
    disable account - Disable Linux user

enable:
    enable log-priority - Enable a logging priority
    enable sessionlog-priority - [Deprecated] Enable a logging priority for a session
    enable root - Enable root user access to a service
    enable feedback - Enable MaxScale feedback to notification service
    enable syslog - Enable syslog logging
    enable maxlog - Enable MaxScale logging
    enable account - Activate a Linux user account for MaxAdmin use

flush:
    flush log - Flush the content of a log file and reopen it
    flush logs - Flush the content of a log file and reopen it

list:
    list clients - List all the client connections to MaxScale
    list dcbs - List all active connections within MaxScale
    list filters - List all filters
    list listeners - List all listeners
    list modules - List all currently loaded modules
    list monitors - List all monitors
    list services - List all services
    list servers - List all servers
    list sessions - List all the active sessions within MaxScale
    list threads - List the status of the polling threads in MaxScale
    list commands - List registered commands

reload:
    reload config - Reload the configuration
    reload dbusers - Reload the database users for a service

restart:
    restart monitor - Restart a monitor
    restart service - Restart a service
    restart listener - Restart a listener

shutdown:
    shutdown maxscale - Initiate a controlled shutdown of MaxScale
    shutdown monitor - Stop a monitor
    shutdown service - Stop a service
    shutdown listener - Stop a listener

show:
    show dcbs - Show all DCBs
    show dbusers - [deprecated] Show user statistics
    show authenticators - Show authenticator diagnostics for a service
    show epoll - Show the polling system statistics
    show eventstats - Show event queue statistics
    show feedbackreport - Show the report of MaxScale loaded modules, suitable for Notification Service
    show filter - Show filter details
    show filters - Show all filters
    show log_throttling - Show the current log throttling setting (count, window (ms), suppression (ms))
    show modules - Show all currently loaded modules
    show monitor - Show monitor details
    show monitors - Show all monitors
    show persistent - Show the persistent connection pool of a server
    show server - Show server details
    show servers - Show all servers
    show serversjson - Show all servers in JSON
    show services - Show all configured services in MaxScale
    show service - Show a single service in MaxScale
    show session - Show session details
    show sessions - Show all active sessions in MaxScale
    show tasks - Show all active housekeeper tasks in MaxScale
    show threads - Show the status of the worker threads in MaxScale
    show users - Show enabled Linux accounts
    show version - Show the MaxScale version number

sync:
    sync logs - Flush log files to disk

call:
    call command - Call module command


Type `help COMMAND` to see details of each command.
Where commands require names as arguments and these names contain
whitespace either the \ character may be used to escape the whitespace
or the name may be enclosed in double quotes ".

To see more details on a particular command, and a list of the sub commands of the command, type help followed by the command name.

MaxScale> help list
Available options to the `list` command:

list clients - List all the client connections to MaxScale

Usage: list clients

----------------------------------------------------------------------------

list dcbs - List all active connections within MaxScale

Usage: list dcbs

----------------------------------------------------------------------------

list filters - List all filters

Usage: list filters

----------------------------------------------------------------------------

list listeners - List all listeners

Usage: list listeners

----------------------------------------------------------------------------

list modules - List all currently loaded modules

Usage: list modules

----------------------------------------------------------------------------

list monitors - List all monitors

Usage: list monitors

----------------------------------------------------------------------------

list services - List all services

Usage: list services

----------------------------------------------------------------------------

list servers - List all servers

Usage: list servers

----------------------------------------------------------------------------

list sessions - List all the active sessions within MaxScale

Usage: list sessions

----------------------------------------------------------------------------

list threads - List the status of the polling threads in MaxScale

Usage: list threads

----------------------------------------------------------------------------

list commands - List registered commands

Usage: list commands [MODULE] [COMMAND]

Parameters:
MODULE  Regular expressions for filtering module names
COMMAND Regular expressions for filtering module command names

Example: list commands my-module my-command

MaxScale>

Working With Services

A service is a very important concept in MariaDB MaxScale as it defines the mechanism by which clients interact with MariaDB MaxScale and can attached to the backend databases. A number of commands exist that allow interaction with the services.

What Services Are Available?

The list services command can be used to discover what services are currently available within your MariaDB MaxScale configuration.

MaxScale> list services
Services.
--------------------------+-------------------+--------+----------------+-------------------
Service Name              | Router Module     | #Users | Total Sessions | Backend databases
--------------------------+-------------------+--------+----------------+-------------------
RWSplit                   | readwritesplit    |      1 |              1 | server1, server2, server3, server4
SchemaRouter              | schemarouter      |      1 |              1 | server1, server2, server3, server4
RWSplit-Hint              | readwritesplit    |      1 |              1 | server1, server2, server3, server4
ReadConn                  | readconnroute     |      1 |              1 | server1
CLI                       | cli               |      2 |              2 |
--------------------------+-------------------+--------+----------------+-------------------
MaxScale>

In order to determine which ports services are using then the list listeners command can be used.

MaxScale> list listeners
Listeners.
----------------------+---------------------+--------------------+-----------------+-------+--------
Name                  | Service Name        | Protocol Module    | Address         | Port  | State
----------------------+---------------------+--------------------+-----------------+-------+--------
RWSplit-Listener      | RWSplit             | MySQLClient        | *               |  4006 | Running
SchemaRouter-Listener | SchemaRouter        | MySQLClient        | *               |  4010 | Running
RWSplit-Hint-Listener | RWSplit-Hint        | MySQLClient        | *               |  4009 | Running
ReadConn-Listener     | ReadConn            | MySQLClient        | *               |  4008 | Running
CLI-Listener          | CLI                 | maxscaled          | default         |     0 | Running
----------------------+---------------------+--------------------+-----------------+-------+--------
MaxScale>

See Service Details

It is possible to see the details of an individual service using the show service command. This command should be passed the name of the service you wish to examine as an argument. Where a service name contains spaces characters there should either be escaped or the name placed in quotes.

MaxScale> show service RWSplit
    Service:                             RWSplit
    Router:                              readwritesplit
    State:                               Started

    use_sql_variables_in:      all
    slave_selection_criteria:  LEAST_CURRENT_OPERATIONS
    master_failure_mode:       fail_instantly
    max_slave_replication_lag: -1
    retry_failed_reads:        true
    strict_multi_stmt:         true
    disable_sescmd_history:    true
    max_sescmd_history:        0
    master_accept_reads:       false

    Number of router sessions:              0
    Current no. of router sessions:         1
    Number of queries forwarded:            0
    Number of queries forwarded to master:  0 (0.00%)
    Number of queries forwarded to slave:   0 (0.00%)
    Number of queries forwarded to all:     0 (0.00%)
    Started:                             Thu Apr 20 09:45:13 2017
    Root user access:                    Disabled
    Backend databases:
        [127.0.0.1]:3000    Protocol: MySQLBackend    Name: server1
        [127.0.0.1]:3001    Protocol: MySQLBackend    Name: server2
        [127.0.0.1]:3002    Protocol: MySQLBackend    Name: server3
        [127.0.0.1]:3003    Protocol: MySQLBackend    Name: server4
    Total connections:                   1
    Currently connected:                 1
MaxScale>

This allows the set of backend servers defined by the service to be seen along with the service statistics and other information.

Examining Service Users

MariaDB MaxScale provides an authentication model by which the client application authenticates with MariaDB MaxScale using the credentials they would normally use to with the database itself. MariaDB MaxScale loads the user data from one of the backend databases defined for the service. The show dbusers command can be used to examine the user data held by MariaDB MaxScale.

MaxScale> show dbusers RWSplit
User names: @localhost @localhost.localdomain 14567USER@localhost monuser@localhost monuser@% 14609USER@localhost maxuser@localhost maxuser@% 14651USER@localhost maxtest@localhost maxtest@% 14693USER@localhost skysql@localhost skysql@% 14735USER@localhost cliuser@localhost cliuser@% repuser@localhost repuser@%
MaxScale>

Reloading Service User Data

MariaDB MaxScale will automatically reload user data if there are failed authentication requests from client applications. This reloading is rate limited and triggered by missing entries in the MariaDB MaxScale table. If a user is removed from the backend database user table it will not trigger removal from the MariaDB MaxScale internal table. The reload dbusers command can be used to force the reloading of the user table within MariaDB MaxScale.

MaxScale> reload dbusers RWSplit
Reloaded database users for service RWSplit.
MaxScale>

Stopping A Service

It is possible to stop a service from accepting new connections by using the shutdown service command. This will not affect the connections that are already in place for a service, but will stop any new connections from being accepted.

MaxScale> shutdown service RWSplit
MaxScale>

Restart A Stopped Service

A stopped service may be restarted by using the restart service command.

MaxScale> restart service RWSplit
MaxScale>

Working With Servers

The server represents each of the instances of MariaDB or MySQL that a service may use.

What Servers Are Configured?

The command list servers can be used to display a list of all the servers configured within MariaDB MaxScale.

MaxScale> list servers
Servers.
-------------------+-----------------+-------+-------------+--------------------
Server             | Address         | Port  | Connections | Status
-------------------+-----------------+-------+-------------+--------------------
server1            | 127.0.0.1       |  3000 |           0 | Master, Running
server2            | 127.0.0.1       |  3001 |           0 | Slave, Running
server3            | 127.0.0.1       |  3002 |           0 | Slave, Running
server4            | 127.0.0.1       |  3003 |           0 | Slave, Running
-------------------+-----------------+-------+-------------+--------------------
MaxScale>

Server Details

It is possible to see more details regarding a given server using the show server command.

MaxScale> show server server2
Server 0x6501d0 (server2)
    Server:                              127.0.0.1
    Status:                              Slave, Running
    Protocol:                            MySQLBackend
    Port:                                3001
    Server Version:                      10.1.22-MariaDB
    Node Id:                             3001
    Master Id:                           3000
    Slave Ids:
    Repl Depth:                          1
    Number of connections:               0
    Current no. of conns:                0
    Current no. of operations:           0
MaxScale>

If the server has a non-zero value set for the server configuration item "persistpoolmax", then additional information will be shown:

    Persistent pool size:            1
    Persistent measured pool size:   1
    Persistent pool max size:        10
    Persistent max time (secs):      3660

The distinction between pool size and measured pool size is that the first is a counter that is updated when operations affect the persistent connections pool, whereas the measured size is the result of checking how many persistent connections are currently in the pool. It can be slightly different, since any expired connections are removed during the check.

Setting The State Of A Server

MariaDB MaxScale maintains a number of status flags for each server that is configured. These status flags are normally maintained by the monitors but there are two commands in the user interface that can be used to manually set these flags; the set server and clear server commands.

Flag Description
running The server is responding to requests, accepting connections and executing database commands
master The server is a master in a replication or it can be used for database writes
slave The server is a replication slave or is considered as a read only database
synced The server is a fully fledged member of a Galera cluster
maintenance The server is in maintenance mode. It won't be used by services or monitored by monitors
stale The server is a stale master server

All status flags, with the exception of the maintenance flag, will be set by the monitors that are monitoring the server. If manual control is required the monitor should be stopped.

MaxScale> set server server3 maintenance
MaxScale> clear server server3 maintenance
MaxScale>

Viewing the persistent pool of DCB

The DCBs that are in the pool for a particular server can be displayed (in the format described below in the DCB section) with a command like:

MaxScale> show persistent server1
Number of persistent DCBs: 0

Working With Sessions

The MariaDB MaxScale session represents the state within MariaDB MaxScale. Sessions are dynamic entities and not named in the configuration file, this means that sessions can not be easily named within the user interface. The sessions are referenced using ID values, these are actually memory address, however the important thing is that no two session have the same ID.

What Sessions Are Active in MariaDB MaxScale?

There are a number of ways to find out what sessions are active, the most comprehensive being the list sessions command.

MaxScale> list sessions
-----------------+-----------------+----------------+--------------------------
Session          | Client          | Service        | State
-----------------+-----------------+----------------+--------------------------
10               | localhost       | CLI            | Session ready for routing
11               | ::ffff:127.0.0.1 | RWSplit        | Session ready for routing
-----------------+-----------------+----------------+--------------------------

MaxScale>

This will give a list of client connections.

Display Session Details

Once the session ID has been determined using one of the above method it is possible to determine more detail regarding a session by using the show session command.

MaxScale> show session 11
Session 11
    State:               Session ready for routing
    Service:             RWSplit
    Client Address:          maxuser@::ffff:127.0.0.1
    Connected:               Thu Apr 20 09:51:31 2017

    Idle:                82 seconds
MaxScale>

Descriptor Control Blocks

The Descriptor Control Block or DCB is a very important entity within MariaDB MaxScale, it represents the state of each connection within MariaDB MaxScale. A DCB is allocated for every connection from a client, every network listener and every connection to a backend database. Statistics for each of these connections are maintained within these DCB’s.

As with session above the DCB’s are not named and are therefore referred to by the use of a unique ID, the memory address of the DCB.

Finding DCB’s

There are several ways to determine what DCB’s are active within a MariaDB MaxScale server, the most straightforward being the list dcbs command.

MaxScale> list dcbs
Descriptor Control Blocks
------------------+----------------------------+--------------------+----------
 DCB              | State                      | Service            | Remote
------------------+----------------------------+--------------------+----------
 0x68c0a0         | DCB for listening socket   | RWSplit            |
 0x6e23f0         | DCB for listening socket   | CLI                |
 0x691710         | DCB for listening socket   | SchemaRouter       |
 0x7fffe40130f0   | DCB in the polling loop    | CLI                | localhost
 0x6b7540         | DCB for listening socket   | RWSplit-Hint       |
 0x6cd020         | DCB for listening socket   | ReadConn           |
 0x7fffd80130f0   | DCB in the polling loop    | RWSplit            | ::ffff:127.0.0.1
 0x7fffdc014590   | DCB in the polling loop    | RWSplit            |
 0x7fffdc0148d0   | DCB in the polling loop    | RWSplit            |
 0x7fffdc014c60   | DCB in the polling loop    | RWSplit            |
 0x7fffdc014ff0   | DCB in the polling loop    | RWSplit            |
------------------+----------------------------+--------------------+----------

MaxScale>

A MariaDB MaxScale server that has activity on it will however have many more DCB’s than in the example above, making it hard to find the DCB that you require. The DCB ID is also included in a number of other command outputs, depending on the information you have it may be easier to use other methods to locate a particular DCB.

DCB Of A Client Connection

To find the DCB for a particular client connection it may be best to start with the list clients command and then look at each DCB for a particular client address to determine the one of interest.

DCB Details

The details of DCBs can be obtained by use of the show dcbs command

DCB: 0x68c0a0
    DCB state:          DCB for listening socket
    Service:            RWSplit
    Role:                     Service Listener
    Statistics:
        No. of Reads:             0
        No. of Writes:            0
        No. of Buffered Writes:   0
        No. of Accepts:           1
        No. of High Water Events: 0
        No. of Low Water Events:  0
DCB: 0x7fffd80130f0
    DCB state:          DCB in the polling loop
    Service:            RWSplit
    Connected to:       ::ffff:127.0.0.1
    Username:           maxuser
    Role:                     Client Request Handler
    Statistics:
        No. of Reads:             5
        No. of Writes:            0
        No. of Buffered Writes:   6
        No. of Accepts:           0
        No. of High Water Events: 0
        No. of Low Water Events:  0
DCB: 0x7fffdc014590
    DCB state:          DCB in the polling loop
    Service:            RWSplit
    Server name/IP:     127.0.0.1
    Port number:        3000
    Protocol:           MySQLBackend
    Server status:            Master, Running
    Role:                     Backend Request Handler
    Statistics:
        No. of Reads:             4
        No. of Writes:            0
        No. of Buffered Writes:   3
        No. of Accepts:           0
        No. of High Water Events: 0
        No. of Low Water Events:  0

The information Username, Protocol, Server Status are not always relevant, and will not be shown when they are null. The time the DCB was added to the persistent pool is only shown for a DCB that is in a persistent pool.

Working with Filters

Filters allow the request contents and result sets from a database to be modified for a client connection, pipelines of filters can be created between the client connection and MariaDB MaxScale router modules.

What Filters Are Configured?

Filters are configured in the configuration file for MariaDB MaxScale, they are given names and may be included in the definition of a service. The list filters command can be used to determine which filters are defined.

MaxScale> list filters
Filters
--------------------+-----------------+----------------------------------------
Filter              | Module          | Options
--------------------+-----------------+----------------------------------------
counter             | testfilter      |
QLA                 | qlafilter       | /tmp/QueryLog
Replicate           | tee             |
QLA_BLR             | qlafilter       | /tmp/QueryLog.blr0
regex               | regexfilter     |
MySQL5.1            | regexfilter     |
top10               | topfilter       |
--------------------+-----------------+----------------------------------------
MaxScale>

Retrieve Details Of A Filter Configuration

The command show filter can be used to display information related to a particular filter.

MaxScale> show filter QLA
Filter 0x719460 (QLA)
    Module: qlafilter
    Options:        /tmp/QueryLog
            Limit logging to connections from       127.0.0.1
            Include queries that match              select.*from.*user.*where
MaxScale>

Filter Usage

The show session command will include details for each of the filters in use within a session. First use list sessions or list clients to find the session of interest and then run the show session command

MaxScale> list sessions
-----------------+-----------------+----------------+--------------------------
Session          | Client          | Service        | State
-----------------+-----------------+----------------+--------------------------
6                | ::ffff:127.0.0.1 | RWSplit-Top    | Session ready for routing
7                | localhost       | CLI            | Session ready for routing
-----------------+-----------------+----------------+--------------------------

MaxScale> show session 6
Session 6
    State:               Session ready for routing
    Service:             RWSplit-Top
    Client Address:          maxuser@::ffff:127.0.0.1
    Connected:               Thu Apr 20 09:58:38 2017

    Idle:                9 seconds
    Filter: Top
        Report size            10
        Logging to file /tmp/top.1.
        Current Top 10:
        1 place:
            Execution time: 0.000 seconds
            SQL: show tables from information_schema
        2 place:
            Execution time: 0.000 seconds
            SQL: show databases
        3 place:
            Execution time: 0.000 seconds
            SQL: show tables
        4 place:
            Execution time: 0.000 seconds
            SQL: select @@version_comment limit 1

The data displayed varies from filter to filter, the example above is the top filter. This filter prints a report of the current top queries at the time the show session command is run.

Working With Monitors

Monitors are used to monitor the state of databases within MariaDB MaxScale in order to supply information to other modules, specifically the routers within MariaDB MaxScale.

What Monitors Are Running?

To see what monitors are running within MariaDB MaxScale use the list monitors command.

MaxScale> list monitors
---------------------+---------------------
Monitor              | Status
---------------------+---------------------
MySQL-Monitor        | Running
---------------------+---------------------
MaxScale>

Details Of A Particular Monitor

To see the details of a particular monitor use the show monitor command.

MaxScale> show monitor MySQL-Monitor
Monitor:           0x6577e0
Name:              MySQL-Monitor
State:             Running
Sampling interval: 10000 milliseconds
Connect Timeout:   3 seconds
Read Timeout:      1 seconds
Write Timeout:     2 seconds
Monitored servers: [127.0.0.1]:3000, [127.0.0.1]:3001, [127.0.0.1]:3002, [127.0.0.1]:3003
MaxScale MonitorId: 0
Replication lag:    disabled
Detect Stale Master:    enabled
Server information

Server: server1
Server ID: 3000
Read only: OFF
Slave configured: NO
Slave IO running: NO
Slave SQL running: NO
Master ID: -1
Master binlog file:
Master binlog position: 0

Server: server2
Server ID: 3001
Read only: OFF
Slave configured: YES
Slave IO running: YES
Slave SQL running: YES
Master ID: 3000
Master binlog file: binlog.000001
Master binlog position: 435

Server: server3
Server ID: 3002
Read only: OFF
Slave configured: YES
Slave IO running: YES
Slave SQL running: YES
Master ID: 3000
Master binlog file: binlog.000001
Master binlog position: 435

Server: server4
Server ID: 3003
Read only: OFF
Slave configured: YES
Slave IO running: YES
Slave SQL running: YES
Master ID: 3000
Master binlog file: binlog.000001
Master binlog position: 435


MaxScale>

Shutting Down A Monitor

A monitor may be shutdown using the shutdown monitor command. This allows for manual control of the status of servers using the set server and clear server commands.

MaxScale> shutdown monitor MySQL-Monitor
MaxScale> list monitors
---------------------+---------------------
Monitor              | Status
---------------------+---------------------
MySQL-Monitor        | Stopped
---------------------+---------------------
MaxScale>

Restarting A Monitor

A monitor that has been shutdown may be restarted using the restart monitor command.

MaxScale> restart monitor MySQL-Monitor
MaxScale> list monitors
---------------------+---------------------
Monitor              | Status
---------------------+---------------------
MySQL-Monitor        | Running
---------------------+---------------------
MaxScale>

MaxScale Status Commands

A number of commands exists that enable the internal MariaDB MaxScale status to be revealed, these commands give an insight to how MariaDB MaxScale is using resource internally and are used to allow the tuning process to take place.

MariaDB MaxScale Thread Usage

MariaDB MaxScale uses a number of threads, as defined in the MariaDB MaxScale configuration file, to execute the processing of requests received from clients and the handling of responses. The show threads command can be used to determine what each thread is currently being used for.

MaxScale> show threads
Polling Threads.

Historic Thread Load Average: 1.06.
Current Thread Load Average: 0.00.
15 Minute Average: 0.10, 5 Minute Average: 0.30, 1 Minute Average: 0.67

Pending event queue length averages:
15 Minute Average: 0.00, 5 Minute Average: 0.00, 1 Minute Average: 0.00

 ID | State      | # fds  | Descriptor       | Running  | Event
----+------------+--------+------------------+----------+---------------
  0 | Polling    |        |                  |          |
  1 | Polling    |        |                  |          |
  2 | Processing |      1 | 0x6e0dd0         | <202400ms | IN|OUT
  3 | Polling    |        |                  |          |
MaxScale>

The resultant output returns data as to the average thread utilization for the past minutes 5 minutes and 15 minutes. It also gives a table, with a row per thread that shows what DCB that thread is currently processing events for, the events it is processing and how long, to the nearest 100ms has been send processing these events.

The Housekeeper Tasks

Internally MariaDB MaxScale has a housekeeper thread that is used to perform periodic tasks, it is possible to use the command show tasks to see what tasks are outstanding within the housekeeper.

MaxScale> show tasks
Name                      | Type     | Frequency | Next Due
--------------------------+----------+-----------+-------------------------
Load Average              | Repeated | 10        | Thu Apr 20 10:02:26 2017
MaxScale>

Administration Commands

What Modules Are In use?

In order to determine what modules are in use, and the version and status of those modules the list modules command can be used.

MaxScale> list modules
Modules.
----------------+-----------------+---------+-------+-------------------------
Module Name     | Module Type     | Version | API   | Status
----------------+-----------------+---------+-------+-------------------------
qc_sqlite       | QueryClassifier | V1.0.0  | 1.1.0 | Beta
MySQLAuth       | Authenticator   | V1.1.0  | 1.1.0 | GA
MySQLClient     | Protocol        | V1.1.0  | 1.1.0 | GA
MaxAdminAuth    | Authenticator   | V2.1.0  | 1.1.0 | GA
maxscaled       | Protocol        | V2.0.0  | 1.1.0 | GA
MySQLBackendAuth| Authenticator   | V1.0.0  | 1.1.0 | GA
MySQLBackend    | Protocol        | V2.0.0  | 1.1.0 | GA
mysqlmon        | Monitor         | V1.5.0  | 3.0.0 | GA
schemarouter    | Router          | V1.0.0  | 2.0.0 | Beta
readwritesplit  | Router          | V1.1.0  | 2.0.0 | GA
topfilter       | Filter          | V1.0.1  | 2.2.0 | GA
readconnroute   | Router          | V1.1.0  | 2.0.0 | GA
cli             | Router          | V1.0.0  | 2.0.0 | GA
----------------+-----------------+---------+-------+-------------------------

MaxScale>

This command provides important version information for the module. Each module has two versions; the version of the module itself and the version of the module API that it supports. Also included in the output is the status of the module, this may be "In Development", “Alpha”, “Beta”, “GA” or “Experimental”.

Enabling syslog and maxlog logging

MariaDB MaxScale can log messages to syslog, to a log file or to both. The approach can be set in the config file, but can also be changed from maxadmin. Syslog logging is identified by syslog and file logging by maxlog.

MaxScale> enable syslog
MaxScale> disable maxlog

NOTE If you disable both, then you will see no messages at all.

Rotating the log file

MariaDB MaxScale logs messages to a log file in the log directory of MariaDB MaxScale. As the log file grows continuously, it is recommended to periodically rotate it. When rotated, the current log file will be closed and a new one with the same name opened.

To retain the earlier log entries, you need to first rename the log file and then instruct MaxScale to rotate it.

$ mv maxscale.log maxscale1.log
$ # MaxScale continues to write to maxscale1.log
$ kill -SIGUSR1 <maxscale-pid>
$ # MaxScale closes the file (i.e. maxscale1.log) and reopens maxscale.log

There are two ways for rotating the log - flush log maxscale and flush logs; the result is identical. The two alternatives are due to historical reasons; earlier MariaDB MaxScale had several different log files.

MaxScale> flush log maxscale
MaxScale> flush logs
MaxScale>

Change MariaDB MaxScale Logging Options

From version 1.3 onwards, MariaDB MaxScale has a single log file where messages of various priority (aka severity) are logged. Consequently, you no longer enable or disable log files but log priorities. The priorities are the same as those of syslog and the ones that can be enabled or disabled are debug, info, notice and warning. Error and any more severe messages can not be disabled.

MaxScale> enable log-priority info
MaxScale> disable log-priority notice
MaxScale>

Please note that changes made via this interface will not persist across restarts of MariaDB MaxScale. To make a permanent change edit the maxscale.cnf file.

Adjusting the Log Throttling

From 2.0 onwards, MariaDB MaxScale will throttle messages that are logged too frequently, which typically is a sign that MaxScale encounters some error that just keeps on repeating. The aim is to prevent the log from flooding. The configuration specifies how many times a particular error may be logged during a period of a specified length, before it is suppressed for a period of a specified other length.

The current log throttling configuration can be queried with

MaxScale> show log_throttling
10 1000 100000

where the numbers are the count, the length (in milliseconds) of the period during which the counting is made, and the length (in milliseconds) of the period the message is subsequently suppressed.

The configuration can be set with

MaxScale> set log_throttling 10 1000 10000

where numbers are specified in the same order as in the show case. Setting any of the values to 0, disables the throttling.

Reloading The Configuration

A command, reload config, is available that will cause MariaDB MaxScale to reload the maxscale.cnf configuration file. Note that not all configuration changes are taken into effect when the configuration is reloaded. Refer to the Configuration Guide for a list of parameters that can be changed with it.

Shutting Down MariaDB MaxScale

The MariaDB MaxScale server may be shutdown using the shutdown maxscale command.

MaxScale> shutdown maxscale
MaxScale>

Runtime Configuration Changes

Starting with the 2.1 version of MaxScale, you can modify the runtime configuration. This means that new objects (servers, listeners, monitors) can be created, altered and removed at runtime.

Servers

Creating a New Server

In order to add new servers into MaxScale, they must first be created. They can be created with the create server command. Any runtime configuration changes to servers are persisted meaning that they will still be in effect even after a restart.

create server - Create a new server

Usage: create server NAME HOST [PORT] [PROTOCOL] [AUTHENTICATOR] [OPTIONS]

Parameters:
NAME          Server name
HOST          Server host address
PORT          Server port (default 3306)
PROTOCOL      Server protocol (default MySQLBackend)
AUTHENTICATOR Authenticator module name (default MySQLAuth)
OPTIONS       Comma separated list of options for the authenticator

The first two parameters are required, the others are optional.

Example: create server my-db-1 192.168.0.102 3306

Adding Servers to Services and Monitors

To add a server to a service or a monitor, use the add server command. Any changes to the servers of a service or a monitor are persisted meaning that they will still be in effect even after a restart.

Servers added to services will only be taken into use by new sessions. Old sessions will only use the servers that were a part of the service when they were created.

add server - Add a new server to a service

Usage: add server SERVER TARGET...

Parameters:
SERVER  The server that is added to TARGET
TARGET  List of service and/or monitor names separated by spaces

A server can be assigned to a maximum of 11 objects in one command

Example: add server my-db my-service "Cluster Monitor"

Removing Servers from Services and Monitors

To remove servers from a service or a monitor, use the remove server command. The same rules about server usage for services that apply to add server also apply to remove server. The servers will only be removed from new sessions created after the command is executed.

remove server - Remove a server from a service or a monitor

Usage: remove server SERVER TARGET...

Parameters:
SERVER  The server that is removed from TARGET
TARGET  List of service and/or monitor names separated by spaces

A server can be removed from a maximum of 11 objects in one command

Example: remove server my-db my-service "Cluster Monitor"

Altering Servers

You can alter server parameters with the alter server command. Any changes to the address or port of the server will take effect for new connections only. Changes to other parameters will take effect immediately.

Please note that in order for SSL to be enabled for a created server, all of the required SSL parameters (ssl, ssl_key, ssl_cert and ssl_ca_cert) must be given in the same command.

alter server - Alter server parameters

Usage: alter server NAME KEY=VALUE ...

Parameters:
NAME      Server name
KEY=VALUE List of `key=value` pairs separated by spaces

This will alter an existing parameter of a server. The accepted values for KEY are:

address               Server address
port                  Server port
monuser               Monitor user for this server
monpw                 Monitor password for this server
ssl                   Enable SSL, value must be 'required'
ssl_key               Path to SSL private key
ssl_cert              Path to SSL certificate
ssl_ca_cert           Path to SSL CA certificate
ssl_version           SSL version
ssl_cert_verify_depth Certificate verification depth

To configure SSL for a newly created server, the 'ssl', 'ssl_cert',
'ssl_key' and 'ssl_ca_cert' parameters must be given at the same time.

Example: alter server my-db-1 address=192.168.0.202 port=3307

Destroying Servers

You can destroy created servers with the destroy server command. Only servers created with the create server command should be destroyed. A server can only be destroyed once it has been removed from all services and monitors.

destroy server - Destroy a server

Usage: destroy server NAME

Parameters:
NAME Server to destroy

Example: destroy server my-db-1

Listeners

Creating New Listeners

To create a new listener for a service, use the create listener command. This will create and start a new listener for a service which will immediately start listening for new connections on the specified port.

Please note that in order for SSL to be enabled for a created listeners, all of the required SSL parameters (ssl, ssl_key, ssl_cert and ssl_ca_cert) must be given. All the create listener parameters do not need to be defined in order for SSL to be enabled. The default parameter can be used to signal that MaxScale should use a default value for the parameter in question.

create listener - Create a new listener for a service

Usage: create listener SERVICE NAME [HOST] [PORT] [PROTOCOL] [AUTHENTICATOR] [OPTIONS]
                       [SSL_KEY] [SSL_CERT] [SSL_CA] [SSL_VERSION] [SSL_VERIFY_DEPTH]

Parameters
SERVICE       Service where this listener is added
NAME          Listener name
HOST          Listener host address (default [::])
PORT          Listener port (default 3306)
PROTOCOL      Listener protocol (default MySQLClient)
AUTHENTICATOR Authenticator module name (default MySQLAuth)
OPTIONS       Options for the authenticator module
SSL_KEY       Path to SSL private key
SSL_CERT      Path to SSL certificate
SSL_CA        Path to CA certificate
SSL_VERSION   SSL version (default MAX)
SSL_VERIFY_DEPTH Certificate verification depth

The first two parameters are required, the others are optional.
Any of the optional parameters can also have the value 'default'
which will be replaced with the default value.

Example: create listener my-service my-new-listener 192.168.0.101 4006

Destroying Listeners

You can destroy created listeners with the destroy listener command. This will remove the persisted configuration and it will not be created on the next startup. The listener is stopped but it will remain a part of the runtime configuration until the next restart.

destroy listener - Destroy a listener

Usage: destroy listener SERVICE NAME

Parameters:
NAME Listener to destroy

The listener is stopped and it will be removed on the next restart of MaxScale

Example: destroy listener my-listener

Monitors

Creating New Monitors

The create monitor command creates a new monitor that is initially stopped. Configure the monitor with the alter monitor command and then start it with the restart monitor command. The user and password parameters of the monitor must be defined before the monitor is started.

create monitor - Create a new monitor

Usage: create monitor NAME MODULE

Parameters:
NAME    Monitor name
MODULE  Monitor module

Example: create monitor my-monitor mysqlmon

Altering Monitors

To alter a monitor, use the alter monitor command. Module specific parameters can also be altered.

alter monitor - Alter monitor parameters

Usage: alter monitor NAME KEY=VALUE ...

Parameters:
NAME      Monitor name
KEY=VALUE List of `key=value` pairs separated by spaces

All monitors support the following values for KEY:
user                    Username used when connecting to servers
password                Password used when connecting to servers
monitor_interval        Monitoring interval in milliseconds
backend_connect_timeout Server coneection timeout in seconds
backend_write_timeout   Server write timeout in seconds
backend_read_timeout    Server read timeout in seconds

This will alter an existing parameter of a monitor. To remove parameters,
pass an empty value for a key e.g. 'maxadmin alter monitor my-monitor my-key='

Example: alter monitor my-monitor user=maxuser password=maxpwd

Destroying Monitors

To destroy a monitor, use the destroy monitor command. All servers need to be removed from the monitor before it can be destroyed. Only created monitors should be destroyed and they will remain a part of the runtime configuration until the next restart.

destroy monitor - Destroy a monitor

Usage: destroy monitor NAME

Parameters:
NAME Monitor to destroy

The monitor is stopped and it will be removed on the next restart of MaxScale

Example: destroy monitor my-monitor

Other Modules

Modules can implement custom commands called module commands. These are intended to allow modules to perform very specific tasks.

To list all module commands, execute list commands in maxadmin. This shows all commands that the modules have exposed. It also explains what they do and what sort of arguments they take.

list commands - List registered commands

Usage: list commands [MODULE] [COMMAND]

Parameters:
MODULE  Regular expressions for filtering module names
COMMAND Regular expressions for filtering module command names

Example: list commands my-module my-command

If no module commands are registered, no output will be generated. Refer to the module specific documentation for more details about module commands.

To call a module commands, execute call command <module> <command> in maxadmin. The <module> is the name of the module and is the command that should be called. The commands take a variable amount of arguments which are explained in the output of list commands.

call command - Call module command

Usage: call command MODULE COMMAND ARGS...

Parameters:
MODULE  The module name
COMMAND The command to call
ARGS... Arguments for the command

To list all registered commands, run 'list commands'.

Example: call command my-module my-command hello world!

An example of this is the dbfwfilter module that implements a rule reloading mechanism as a module command. This command takes a filter name as a parameter.

maxadmin call command dbfwfilter rules/reload my-firewall-filter /home/user/rules.txt

Here the name of the filter is my-firewall-filter and the optional rule file path is /home/user/rules.txt.

Tuning MariaDB MaxScale

The way that MariaDB MaxScale does its polling is that each of the polling threads, as defined by the threads parameter in the configuration file, will call epoll_wait to obtain the events that are to be processed. The events are then added to a queue for execution. Any thread can read from this queue, not just the thread that added the event.

Once the thread has done an epoll call with no timeout it will either do an epoll_wait call with a timeout or it will take an event from the queue if there is one. These two new parameters affect this behavior.

The first parameter, which may be set by using the non_blocking_polls option in the configuration file, controls the number of epoll_wait calls that will be issued without a timeout before MariaDB MaxScale will make a call with a timeout value. The advantage of performing a call without a timeout is that the kernel treats this case as different and will not rescheduled the process in this case. If a timeout is passed then the system call will cause the MariaDB MaxScale thread to be put back in the scheduling queue and may result in lost CPU time to MariaDB MaxScale. Setting the value of this parameter too high will cause MariaDB MaxScale to consume a lot of CPU when there is infrequent work to be done. The default value of this parameter is 3.

This parameter may also be set via the maxadmin client using the command set nbpolls <number>.

The second parameter is the maximum sleep value that MariaDB MaxScale will pass to epoll_wait. What normally happens is that MariaDB MaxScale will do an epoll_wait call with a sleep value that is 10% of the maximum, each time the returns and there is no more work to be done MariaDB MaxScale will increase this percentage by 10%. This will continue until the maximum value is reached or until there is some work to be done. Once the thread finds some work to be done it will reset the sleep time it uses to 10% of the maximum.

The maximum sleep time is set in milliseconds and can be placed in the [maxscale] section of the configuration file with the poll_sleep parameter. Alternatively it may be set in the maxadmin client using the command set pollsleep <number>. The default value of this parameter is 1000.

Setting this value too high means that if a thread collects a large number of events and adds to the event queue, the other threads might not return from the epoll_wait calls they are running for some time resulting in less overall performance. Setting the sleep time too low will cause MariaDB MaxScale to wake up too often and consume CPU time when there is no work to be done.

The show epoll command can be used to see how often we actually poll with a timeout, the first two values output are significant. Also the "Number of wake with pending events" is a good measure. This is the count of the number of times a blocking call returned to find there was some work waiting from another thread. If the value is increasing rapidly reducing the maximum sleep value and increasing the number of non-blocking polls should help the situation.

MaxScale> show epoll

Poll Statistics.

No. of epoll cycles:                           343
No. of epoll cycles with wait:                 66
No. of epoll calls returning events:           19
No. of non-blocking calls returning events:    10
No. of read events:                            2
No. of write events:                           15
No. of error events:                           0
No. of hangup events:                          0
No. of accept events:                          4
No. of times no threads polling:               4
Total event queue length:                      1
Average event queue length:                    1
Maximum event queue length:                    1
No of poll completions with descriptors
    No. of descriptors  No. of poll completions.
     1          19
     2          0
     3          0
     4          0
     5          0
     6          0
     7          0
     8          0
     9          0
    >= 10           0
MaxScale>

If the "Number of DCBs with pending events" grows rapidly it is an indication that MariaDB MaxScale needs more threads to be able to keep up with the load it is under.

The show threads command can be used to see the historic average for the pending events queue, it gives 15 minute, 5 minute and 1 minute averages. The load average it displays is the event count per poll cycle data. An idea load is 1, in this case MariaDB MaxScale threads and fully occupied but nothing is waiting for threads to become available for processing.

The show eventstats command can be used to see statistics about how long events have been queued before processing takes place and also how long the events took to execute once they have been allocated a thread to run on.

MaxScale> show eventstats

Event statistics.
Maximum queue time:             000ms
Maximum execution time:         000ms
Maximum event queue length:     1
Total event queue length:       4
Average event queue length:     1

               |    Number of events
Duration       | Queued     | Executed
---------------+------------+-----------
 < 100ms       | 27         | 26
  100 -  200ms | 0          | 0
  200 -  300ms | 0          | 0
  300 -  400ms | 0          | 0
  400 -  500ms | 0          | 0
  500 -  600ms | 0          | 0
  600 -  700ms | 0          | 0
  700 -  800ms | 0          | 0
  800 -  900ms | 0          | 0
  900 - 1000ms | 0          | 0
 1000 - 1100ms | 0          | 0
 1100 - 1200ms | 0          | 0
 1200 - 1300ms | 0          | 0
 1300 - 1400ms | 0          | 0
 1400 - 1500ms | 0          | 0
 1500 - 1600ms | 0          | 0
 1600 - 1700ms | 0          | 0
 1700 - 1800ms | 0          | 0
 1800 - 1900ms | 0          | 0
 1900 - 2000ms | 0          | 0
 2000 - 2100ms | 0          | 0
 2100 - 2200ms | 0          | 0
 2200 - 2300ms | 0          | 0
 2300 - 2400ms | 0          | 0
 2400 - 2500ms | 0          | 0
 2500 - 2600ms | 0          | 0
 2600 - 2700ms | 0          | 0
 2700 - 2800ms | 0          | 0
 2800 - 2900ms | 0          | 0
 2900 - 3000ms | 0          | 0
 > 3000ms      | 0          | 0
MaxScale>

The statics are defined in 100ms buckets, with the count of the events that fell into that bucket being recorded.

Comments

Comments loading...