drbd-user May 2010 archive
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drbd-user: Re: [DRBD-user] DRBD primary/primary for KVM - what i

Re: [DRBD-user] DRBD primary/primary for KVM - what is the best option?

From: Bart Coninckx <bart.coninckx_at_nospam>
Date: Tue May 11 2010 - 16:52:24 GMT
To: Michael Iverson <miverson@4hatteras.com>

On Tuesday 11 May 2010 16:09:08 Michael Iverson wrote:
> ietadm is the answer.
>
> These might help:
>
> http://old.nabble.com/IET-on-DRBD-howto--td20567810.html
> http://www.gossamer-threads.com/lists/linuxha/users/45280
> http://www.markround.com/archives/50-Building-a-redundant-iSCSI-and-NFS-clu
> ster-with-Debian-Part-4.html
>
> On Tue, May 11, 2010 at 9:51 AM, Bart Coninckx <bart.coninckx@telenet.be>
wrote:
> > On Tuesday 11 May 2010 15:15:34 Michael Iverson wrote:
> >> I've done about zero research into this, but perhaps you could run two
> >> separate daemon instances, one listening on each IP.
> >>
> >> On Tue, May 11, 2010 at 8:55 AM, Bart Coninckx
> >
> > <bart.coninckx@telenet.be>wrote:
> >> > On Tuesday 11 May 2010 12:58:45 Michael Iverson wrote:
> >> > > I'd be quite interested as well, obviously. So this is what we would
> >> > > end up with:
> >> > >
> >> > > Host A is primary for drbd volume 1, and secondary for drbd volume
> >> > > 2. It acts as an iSCSI target for whatever's on volume 1.
> >> > >
> >> > > Host B is primary for volume 2, and secondary for volume 1. It acts
> >> > > as a target for whatever's on volume 2.
> >> > >
> >> > > If either node fails, the opposite node takes over the secondary
> >> > > volume, and exports its fallen comrade's iSCSI targets.
> >> > >
> >> > > This idea could possibly be extended with Ben's approach of one DRBD
> >> > > volume per iSCSI target. (Except that it would be in a
> >> > > primary/secondary role, instead of primary/primary.) This would make
> >> > > the process of rebalancing the load between the two nodes fairly
> >> > > trivial.
> >> > >
> >> > > Mike
> >> > >
> >> > > On Tue, May 11, 2010 at 5:09 AM, Bart Coninckx
> >> > > <bart.coninckx@telenet.be
> >> >
> >> > wrote:
> >> > > >> It is. I'm planning to showcase this in one of our upcoming
> >> > > >> webinars.
> >> > > >>
> >> > > >> Cheers,
> >> > > >> Florian
> >> > > >
> >> > > > Excellent, any timeframe on this? As it happens I'm dealing with a
> >> >
> >> > setup
> >> >
> >> > > > now that could definitely benefit from this.
> >> > > >
> >> > > > B.
> >> > > > _______________________________________________
> >> > > > drbd-user mailing list
> >> > > > drbd-user@lists.linbit.com
> >> > > > http://lists.linbit.com/mailman/listinfo/drbd-user
> >> >
> >> > Agreed, but what might be less trivial is to convince a running IETD
> >> > target to
> >> > have the config for the "other" targets merged to the existing targets
> >> > and at
> >> > the same time bind to the new secondary IP address, preferably while
> >> > not breaking running operation. This all should be taken care of by
> >> > Heartbeat.
> >> >
> >> > I'm going to try to dive into the challenge and report back to the
> >> > list, unless the webinar would happen fairly soon.
> >> >
> >> >
> >> > B.
> >> > _______________________________________________
> >> > drbd-user mailing list
> >> > drbd-user@lists.linbit.com
> >> > http://lists.linbit.com/mailman/listinfo/drbd-user
> >
> > Not possible:
> >
> > http://sourceforge.net/mailarchive/message.php?msg_id=02dd01c8263f%244496
> >ae60%245dd810d1%40e3demo
> >
> >
> > Rgds,
> >
> > B.
> > _______________________________________________
> > drbd-user mailing list
> > drbd-user@lists.linbit.com
> > http://lists.linbit.com/mailman/listinfo/drbd-user
>

Building a HA lcuster with IETD and DRBD is not really challenging, has been
done numerous times. The challenge would be having a active/passive one on
which each node is both active for some LUNs and active for others, especially
at failover.

I don't quite get the suggestion on the first link, having a active-active one
and both nodes serving stuff. But I guess it would not distribute load in
between two nodes, what my fist idea would do.

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