[DRBD-user] [Q] DRBD - resyncing after changes to underlying device

Lars Ellenberg Lars.Ellenberg at linbit.com
Wed Jul 13 14:31:49 CEST 2005

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

/ 2005-07-12 11:17:44 +0200
\ Martin Bene:
> Hi Guy,
> > Short version:
> > If a DRBD-controlled underlying block device (/dev/hda3, for example)
> > is mounted directly without DRBD running, the data is changed, then
> > DRBD is reinstated using that block device, will DRBD recognise the
> > changes?
> No, drbd will NOT recognise the changes without intervention; you'll
> need a fullsync to get into a consistent state.
> * shut down drbd on the secondary.
> * install & start drbd on the primary, make drbd primary. Secondary
> should still be down (to make extra sure you don't get a resync in the
> wrong direction).
> * with drbd mounted & primary on the node with the changed data, start
> drbd on the secondary.
> * issue drbdadm invalidate on the secondary to force a fullsync. Once
> that finishes you're back in business with consistent data on both
> nodes.

Thanks, Martin.

I'd even do the invalidate on the secondary _first_ (thats before it
ever had a chance to connect).  And I'd probably use an explicit
"--human" (well, answering "Yes" to the infamous drbd boot script
question would to that implicitly anyways) to the "make primary".


: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
: Schoenbrunner Str. 244, A-1120 Vienna/Europe   http://www.linbit.com :
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