[DRBD-user] DRBD stability issues

Lars Ellenberg lars.ellenberg at linbit.com
Thu Nov 17 11:19:43 CET 2011

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

On Thu, Nov 17, 2011 at 09:18:31AM +0100, Florian Haas wrote:
> On 11/17/11 09:06, Nick Morrison wrote:
> > 
> > On 16 Nov 2011, at 21:01, Florian Haas wrote:
> > 
> >>> The multi volume feature is quite useful. With this I can for example
> >>> switch Primary/Secondary individually if mysql or pgsql crashed without
> >>> affecting each other. 
> >>
> >> Well _that_ you really don't need multi-volume for. :) You could have
> >> done that with just two independent resources (with 8.3, as well).

Actually, you *can not* do that with multiple volumes within one resource.
Or, if you could, that would be a bug.
Volumes within one resource are supposed to be active on the same side.

> > How many resources can I make?  I have 12 so far (one per virtual
> > machine.)  The machines seem to be coping ok.  Is there any limit,
> > arbitrary or otherwise?
> The number of available DRBD devices is set by the "minor_count" module
> parameter. The default, iirc, is 32.

Which means you can use up to 256 (or 255, not so sure there)
DRBD minors with 8.3.

With 8.4, you can use "arbitrarily" many minor devices (one million, in
theory), minor_count is a hint only with 8.4, not a hard limit anymore.

: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com

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