[DRBD-user] Recovery from split-brain condition, please advice.

Ivan ivan.teliatnikov at gmail.com
Mon Nov 16 15:06:31 CET 2009


Hello everyone!

I am new to DRBD and to this list. I recently picked up HA + drbd 2
node cluster that suffered split-brain condition over 6 months ago.
During this time the healthy node continued to work as a file server,
whilst the second node has both HA and drpd turned off.

Primary node:      ( working in production )
Secondary node: rubble     ( has being off-line for 6 motnhs )

------------- state, dstate, cstate of primary node --------------------

[root at flintstone ~]# drbdadm state all
Primary/Unknown

[root at flintstone ~]# drbdadm dstate all
UpToDate/DUnknown

[root at flintstone ~]# drbdadm cstate all
StandAlone

------------- state, dstate, cstate of secondary ( not working ) node
--------------------

[root at rubble init.d]# drbdadm state all
Secondary/Unknown

[root at rubble init.d]# drbdadm dstate all
UpToDate/DUnknown

[root at rubble ~]# drbdadm cstate all
WFConnection

As far as I understand a recovery steps below will guaranty recovery
from split-brain condition.

1. # umount block devices

2. # disconnect all resources on both nodes
$ drbdadm disconnect all

3. # force both nodes to be secondary
$ drbdadm secondary all

4. # select slave drive and tell it to drop all data
$ drbdadm -- --discard-my-data connect resource
to force all resources on the secondary node ( bad ) to be secondary
and to drop all date.

5. # select source and master mode and start synchronisation.
$ drbdadm -- --overwrite-data-of-peer primary resource

6. # Start synchronisation on the source ( master ) node
drbdadm connect resource


I would greatly appreciate if you can answer my questions.

1. Any comments on the procedure?

2. How do I know if --discard-my-date option is necessary ?

3. I wonder if "--" is required after drbdamin? It is mentioned in the
on-line version of DRBD User's guide, whilst man file for drbdadm does
not mention it.

3. After DRBD starts process of synchronisation, can I mount block
devises on the master node, or do I have to wait until synchronisation
is completed?

Thank you very much for your help.

Ivan


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