Configuring the CTDB recovery lock: Difference between revisions

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(Created page with "= Goal = Configure CTDB to use a recovery lock to avoid a "split-brain" situation. = Prerequisites = * Setting up a cluster filesystem (by default - see below) = CTDB...")
 
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= CTDB configuration =
= CTDB configuration =


The recovery lock, configured via <code>CTDB_RECOVERY_LOCK</code> provides important split-brain prevention and is usually configured to point to a lock file in the cluster filesystem. See the RECOVERY LOCK section in [http://ctdb.samba.org/manpages/ctdb.7.html ctdb(7)] for more details.
The recovery lock, configured via the <code>recovery lock</code> option in the <code>cluster</code> section, provides important split-brain prevention and is usually configured to point to a lock file in the cluster filesystem. See the RECOVERY LOCK section in [http://ctdb.samba.org/manpages/ctdb.7.html ctdb(7)] for more details.


For example:
For example:

[cluster]
recovery lock = /clusterfs/.ctdb/reclock

If the clustered filesystem does not support locking on default, CTDB allows to replace this mechanism with a binary that would interact with the clustered filesystem directly. This binary will be launched on each node and the node that can lock the file (or alternative operation) will output "0" (holding lock), the other nodes will output "1" (contended). See the RECOVERY LOCK section in [http://ctdb.samba.org/manpages/ctdb.7.html ctdb(7)] for more info about this mechanism. In the utils directory in the [https://github.com/samba-team/samba/tree/master/ctdb/utils Samba Github] repository additional examples can be found.

== Samba &le; 4.8 ==

The equivalent <code>ctdbd.conf</code> option is <code>CTDB_RECOVERY_LOCK</code>. For example:


CTDB_RECOVERY_LOCK=/clusterfs/.ctdb/reclock
CTDB_RECOVERY_LOCK=/clusterfs/.ctdb/reclock

Revision as of 08:50, 28 November 2018

Goal

Configure CTDB to use a recovery lock to avoid a "split-brain" situation.

Prerequisites

CTDB configuration

The recovery lock, configured via the recovery lock option in the cluster section, provides important split-brain prevention and is usually configured to point to a lock file in the cluster filesystem. See the RECOVERY LOCK section in ctdb(7) for more details.

For example: 

 [cluster]
   recovery lock = /clusterfs/.ctdb/reclock

If the clustered filesystem does not support locking on default, CTDB allows to replace this mechanism with a binary that would interact with the clustered filesystem directly. This binary will be launched on each node and the node that can lock the file (or alternative operation) will output "0" (holding lock), the other nodes will output "1" (contended). See the RECOVERY LOCK section in ctdb(7) for more info about this mechanism. In the utils directory in the Samba Github repository additional examples can be found.

Samba ≤ 4.8

The equivalent ctdbd.conf option is CTDB_RECOVERY_LOCK. For example: 

 CTDB_RECOVERY_LOCK=/clusterfs/.ctdb/reclock
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