On Wed, Jul 09, 2014 at 09:40:59AM +0200, Lars Ellenberg wrote:
> On Wed, Jul 09, 2014 at 09:26:49AM +0200, Lars Ellenberg wrote:
> > On Wed, Jul 09, 2014 at 01:58:05AM +0000, Senne Vaeyens wrote:
> > > Hi,
> > >
> > > I’m using 8.4.4 on CentOS 6.5
> > > I try to configure an NFS server as explained by Craig Carl in the
> > > following presentation:
> > > http://www.slideshare.net/AmazonWebServices/nfs-and-cifs-options-for-aws-stg401-aws-reinvent-2013
> > > , (youtube video of the presentation can be found here:
> > > https://www.youtube.com/watch?v=xbuiIwEOCAs)
> >
> > Yeah, well, IMO, that is tecnically nonsense.
>
> Ok, that may come accross as rude or harsh.
>
> What I mean is, DRBD is NOT a host based mirroring solution,
> but a replication solution, which is not the same thing.
>
> If you want to do host based mirroring, use md raid.
>
> If you want to do replication, between instances,
> use DRBD.
>
> You can clearly use DRBD to *replicate* from one instance
> in one zone to an other instance in an other zone,
> or from instance on "fast" storage to instance on "durable" storage.
>
> This makes perfectly sense.
> This is what DRBD was designed for.
And, now that I watched the video,
that is even what Craig actually suggests to do.
Replicating from one instance in zone a to an other instance in zone b.
So do that ;-)
But don't believe what he says about oos (out-of-sync).
IF you have "oos" != 0 in /proc/drbd,
you are not "behind",
but the respective target volume is *inconsistent* for that many blocks.
> But, in my opinion, you should not try to use DRBD to "mirror" from one
> block storage to an other block storage *within the same instance*.
> For that, md raid would likely be the better solution.
> That is what md raid has been designed for.
>
> I'm clearly biased towards DRBD,
> and I'm happy to hear that you all like to use DRBD.
> But, even if it can do something,
> it is not always the best fit.
> Not for everything.
>
> Simply use the right tool for the job.
>
> > > Craig explains on slide 12 how you configure a local mirror with brbd;
> > >
> > > It goes somewhat like this...
> > >
> > > resource r0 {
> > > on az-a{
> > > device /dev/drbd0;
> > > disk /dev/md0;
> > > address 10.1.1.1:7789;
> > > meta-disk internal;
> > > }
> > > on az-a{
> > > device /dev/drbd1;
> > > disk /dev/md1;
> > > address 10.1.1.1:7789;
> > > meta-disk internal;
> > > }
> > > }
> >
> > Which is simply wrong and won't even parse.
> > So why don't you ask Craig how he really did it?
> > Clearly not the way he presented it in those slides.
> >
> > But see there:
> > http://www.gossamer-threads.com/lists/drbd/users/26473#26473
> >
> > Still, it does not make sense.
> > DRBD is the wrong tool for the job.
> > Use md raid for host based mirroring.
> >
> >
> > --
> > : Lars Ellenberg
> > : LINBIT | Your Way to High Availability
> > : DRBD/HA support and consulting http://www.linbit.com
> >
> > DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
> > __
> > please don't Cc me, but send to list -- I'm subscribed
> > _______________________________________________
> > drbd-user mailing list
> > drbd-user@lists.linbit.com
> > http://lists.linbit.com/mailman/listinfo/drbd-user
>
> --
> : Lars Ellenberg
> : LINBIT | Your Way to High Availability
> : DRBD/HA support and consulting http://www.linbit.com
>
> DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
> __
> please don't Cc me, but send to list -- I'm subscribed
> _______________________________________________
> drbd-user mailing list
> drbd-user@lists.linbit.com
> http://lists.linbit.com/mailman/listinfo/drbd-user
--
: Lars Ellenberg
: LINBIT | Your Way to High Availability
: DRBD/HA support and consulting http://www.linbit.com
DRBD® and LINBIT® are registered trademarks of LINBIT, Austria.
__
please don't Cc me, but send to list -- I'm subscribed
_______________________________________________
drbd-user mailing list
drbd-user@lists.linbit.com
http://lists.linbit.com/mailman/listinfo/drbd-user
