[DRBD-user] DRBD volumes have different files, but DRBD reports them being in sync

Nik Martin nik.martin at nfinausa.com
Sun Sep 2 16:43:14 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On 09/01/2012 03:24 PM, Bala Ramakrishnan wrote:
> I have a DRBD installation on two machines running Centos 6.3 and DRBD 8.4.1
> I have a single resource 'agalaxy' being synced across these two machines. This resource has two volumes:
> Volume 0: /dev/drbd0 mounted on /a10data
> And
> Volume 1: /dev/drbd1 mounted on /a10.
> Volume 0 is running Postgres. I did a lot of other activities with DRBD shutdown. However after a while, I found that the contents in the directory /a10data on one of the machines was different (some intermediate level directories were missing), yet DRBD (cat /proc/drbd) reported that the file systems were in sync.
> Ultimately, I had to re-initialize and resync the volume by invalidating it:
> Drbdadm invalidate agalaxy/0
> Has anyone run into this kind of issue?

You are using LVM Logical Volumes as a DRBD backing device, so you can't 
treat them like physical devices.

DRBD must make a volume snapshot prior to and after syncing, that's why 
you are getting out of sync.

Check this section on LVM as a backing 
store:http://www.drbd.org/users-guide/s-lvm-snapshots.html There are 
handlers you have to use to use LVM as a backing store.


Nik Martin
VP Business Development
Nfina Technologies, Inc.
+ x1003
Relentless Reliability

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