[PATCH] ctdb-recovery: Update timeout and number of retries during recovery

Amitay Isaacs amitay at gmail.com
Fri Jun 3 05:25:40 UTC 2016


The timeout RecoverTimeout (default 120) is used for control messages
sent during the recovery.  If any of the nodes does not respond to any
of the recovery control messages for RecoverTimeout seconds, then it
will cause a failure of recovery of a database.  Recovery helper will
retry the recovery for a database 5 times.

In the worst case, if a database could not be recovered within 5 attempts,
a total of 600 seconds would have passed.  During this time period other
timeouts will be triggered causing unnecessary failures as follows:

1. During the recovery, even though recoverd is processing events,
   it does not send a ping message to ctdb daemon.  If a ping message is
   not received for RecdPingTimeout (default 60) seconds, then ctdb will
   count it as unresponsive recovery daemon.  If the recovery daemon
   fails for RecdFailCount (default 10) times, then ctdb daemon will
   restart recovery daemon.  So after 600 seconds, ctdb daemon will
   restart recovery daemon.

2. If ctdb daemon stays in recovery for RecoveryDropAllIPs (default 120),
   then it will drop all the public addresses.  This will cause all
   SMB client to be disconnected unnecessarily.  The released public
   addresses will not be taken over till the recovery is complete.

To avoid dropping of IPs and restarting recovery daemon during a delayed
recovery, adjust RecoverTimeout to 30 seconds and limit number of
retries for recovering a database to 3.  If we don't hear from a node
for more than 25 seconds, then the node is considered disconnected.
So 30 seconds is sufficient timeout for controls during recovery.

Please review and push.

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