[DRBD-user] What generation counters look like?

Lars Ellenberg Lars.Ellenberg at linbit.com
Mon Nov 27 18:24:00 CET 2006

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

/ 2006-11-27 19:54:38 +0300
\ Igor Yu. Zhbanov:
> Hello!
> I want to better understand how drbd decides what node has more fresh data.
> Sometimes after reboots in the cluster there was situation when drbd on
> master node (which was in Primary state already) refuses to connect with
> drbd on slave node, claiming that "Primary shall become SyncTarget".
> Even if I write some files on promary (to make changes on device) it refuses
> to connect anyway.
> So, what is generation counters? (I just don't want to grep though drbd
> sources. ;-) Is it belongs to whole drbd device or each block has its own
> counter? Is it like time stamp or like version number?

version 0.7 and before uses "generation counters".
the concept is explained in
 drbd_paper_for_NLUUG_2001.pdf (or something like that)
and has little changed since.

version 8 uses uuid tags.
the concept is explained in the drbd8 pdf

: Lars Ellenberg                                  Tel +43-1-8178292-0  :
: LINBIT Information Technologies GmbH            Fax +43-1-8178292-82 :
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