Galera Black Box
The Galera Black Box is a MariaDB Enterprise Server feature that keeps recent debug log messages in a shared-memory ring buffer so they survive a crash and can be analyzed with mariadb-bbtool.
Overview
The Black Box is an in-memory (shared-memory) ring buffer that continuously records debug log messages. Because it lives in shared memory rather than in the server process, its contents survive a server crash and can be examined afterwards, which helps support and developers diagnose hard-to-reproduce failures, including in Galera Cluster.
It is disabled by default. To enable it, set a non-zero wsrep_black_box_size.
Enabling the Black Box
Configure the size (in bytes) and, optionally, the name in an options file:
[mariadb]
wsrep_black_box_size = 10485760
wsrep_black_box_name = bb-mariadbwsrep_black_box_size — size in bytes.
0(default) means no Black Box is created. It is dynamic: changing it at runtime re-creates the Black Box at the new size.wsrep_black_box_name — the name of the shared-memory object (default
bb-mariadb). Read-only; set at startup only.
When the server starts, it opens the Black Box in the data directory. If a Black Box with the same name already exists (for example, left behind by a crashed server), its contents are first written to a dump file in the data directory and then it is re-created empty.
Inspecting the Black Box with mariadb-bbtool
The mariadb-bbtool utility, installed alongside the server, operates on a Black Box by name:
mariadb-bbtool <name> <command>dump
Print the Black Box contents to standard output
status
Report the Black Box state
enable
Put the Black Box into the operational state
disable
Put the Black Box into the disabled state
delete
Remove the active Black Box
Run mariadb-bbtool --help for usage. A Black Box is in one of three states: Closed, Disabled, or Operational.
For example, to dump the running server's Black Box:
See Also
This page is licensed: CC BY-SA / Gnu FDL
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