[DRBD-user] 3 simple questions for a nifty setup

[Lars Ellenberg]

/ 2005-08-24 20:01:58 +0100
\ paddy:
> > > Sorry, I missed the bit earlier about having multiple secondaries in drbd.
> > > 
> > > As you know, I had assumed that this is not possible with 0.7, but I don't
> > > recall exactly why.
> > 
> > in short, because reliable multicast is tricky.
> 
> I have only heard of it.
> 
> Do you get all the magic out of the networking or do you have to do 
> more work in drbd itself ?

to my knowledge, there currently is no (at least no open source)
implementation of such a thing that would be usable by drbd.
yes, we pretty much would have to (re)invent it ourselves.

> > we have paying customers where we do a "tripple legged, two secondary" setup,
> > but that is currently no so much for availability than for desaster recovery
> > backup purposes.
> 
> Cool!
> What happens at fail-over ? are they primary/secondary/tertiary ?

buy it, and I'll tell you :->

well, basically, in case they'd need the "tertiary", what would happen is,
they phone us, and we do the tricky bit. *g*

as I said, the "tertiary" is for desaster recovery, not for "high"
availability, so in case it is needed, there already has been a
desaster, and the additional latency of getting us involved is ok
compared to everything else.

you really do not want to have automatic failover to a distant data center
just because heartbeat feels like it...

cheers,

-- 
: 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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