[DRBD-user] Content of DRBD volume is invalid during sync after disk replace

[Igor Cicimov]

Hi,

On Fri, Jul 27, 2018 at 1:36 AM, Lars Ellenberg <lars.ellenberg at linbit.com>
wrote:

> On Mon, Jul 23, 2018 at 02:46:25PM +0200, Michal Michaláč wrote:
> >                  Hello,
> >
> >
> >
> > after replacing backing device of DRBD, content of DRBD volume (not only
> > backing disk) is invalid on node with inconsistent backing device, until
> > sync finishes. I think, correct behaviour is to read data from peer's
> > (consistent) backing device if process running on node with inconsistent
> > backing device wants to read unsynchronized part of DRBD volume.
>
> ...
>
> > If I  skip create-md (step 4), situation is even worse - after attach
> disk,
> > DRBD says volume is sychronized(!):
> >
> > log: Began resync as SyncTarget (will sync 0 KB [0 bits set])
> >
> > but after verification (drbdadm verify test), there are many out-of-sync
> > sectors.
> >
> > After disconnect/connect volume test, resync not started(!):
> >
> > log: No resync, but 3840 bits in bitmap!
> >
> > If I (on new DRBD volume) just disconnect -> write changes to primary ->
> > connect, sync works correctly.
>
> > Versions (on both nodes are identical):
> > # cat /proc/drbd
> > version: 9.0.14-1 (api:2/proto:86-113)
> > GIT-hash: 62f906cf44ef02a30ce0c148fec223b40c51c533 build by root at n2,
> > 2018-07-12 13:18:02
> >
> > Transports (api:16): tcp (9.0.14-1)
> >
> > # uname -a
> > Linux n2 4.15.17-1-pve #1 SMP PVE 4.15.17-9 (Wed, 9 May 2018 13:31:43
> +0200)
> > x86_64 GNU/Linux
> >
> > # lvm version
> >   LVM version:     2.02.168(2) (2016-11-30)
> >   Library version: 1.02.137 (2016-11-30)
> >   Driver version:  4.37.0
>
> > Is it bug or am I doing something wrong?
>
> Thanks for the detailed and useful report,
> definetely a serious and embarassing bug,
> now already fixed internally.
> Fix will go into 9.0.15 final.
> We are in the progress of making sure
> we have covered all variants and lose ends of this.
>

​Is this going to get back ported to 8.4 as well?​
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