[DRBD-user] Resync

Lars Ellenberg Lars.Ellenberg at linbit.com
Mon Aug 14 17:20:21 CEST 2006

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

/ 2006-08-14 15:50:53 +0200
\ John Lauwers:
> >
> > what exactly is the sequence of events if it does not work?
> > (please, not "the same thing but...", but write it down.
> >  each step you do. what you did expect. and what happend.)
> OK,
> Node 1 Primary
> Node 2 Secondary
> I have Samba server running on node1.
> I go to a windows computer I open a file that is on a samba share, and
> change its contents.
> I pull the plug of node1. I go look to the same file on the samba share and
> I see that the file is correct (repliction did his work).
> I change the contents of the file (which is now the file on node2) and I
> save it.
> When I then put the plug back in node1, when I then look at the file it is
> the old file again.
> The file is the same file before I pulled the network plug.
> The file is NOT replicated on the node1.
> So my last changes had no effect

sorry, sir.
I said step by step.
thats not what you did.
what plug did you pull?
when did what(heartbeat) change whom to secondary or primary?

you know what
  single failure
  multiple failure
  multiple communication channels

look also into your heartbeat (debug) logs.

from the log provided, you provoked a split brain, you had no stonith,
you did independendly multiple actions on both servers while they were
not connected and could not communicate, and both nodes have been switched
into secondary state again before reconnecting.

we try to handle detection of splitbrain better in drbd 8 using uuid
tagged data generations, but drbd 0.7 still does event counter based data
generations, and so if independent events happen on both boxes while they
are not connected, the "magic" to detect which is the newest data
generation is likely to fail; they may even decide that they don't need
any sync at all while they have completely different data sets.
so don't do that.

: 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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