Re: RBD Mirror DR Testing

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On Thu, Nov 21, 2019 at 9:56 AM Jason Dillaman <jdillama@xxxxxxxxxx> wrote:
>
> On Thu, Nov 21, 2019 at 8:49 AM Vikas Rana <vrana@xxxxxxxxxxxx> wrote:
> >
> > Thanks Jason for such a quick response. We are on 12.2.10.
> >
> > Checksuming a 200TB image will take a long time.
>
> How would mounting an RBD image and scanning the image be faster? Are
> you only using a small percentage of the image?

... and of course, you can mount an RBD snapshot in read-only mode.

> > To test the DR copy by mounting it, these are the steps I'm planning to follow
> > 1. Demote the Prod copy and promote the DR copy
> > 2. Do we have to recreate the rbd mirror relationship going from DR to primary?
> > 3. Mount and validate the data
> > 4. Demote the DR copy and promote the Prod copy
> > 5. Revert the peer relationship if required?
> >
> > Did I do it right or miss anything?
>
> You cannot change the peers or you will lose the relationship. If you
> insist on your course of action, you just need to be configured for
> two-way mirroring and leave it that way.
>
> >
> > Thanks,
> > -Vikas
> >
> > -----Original Message-----
> > From: Jason Dillaman <jdillama@xxxxxxxxxx>
> > Sent: Thursday, November 21, 2019 8:33 AM
> > To: Vikas Rana <vrana@xxxxxxxxxxxx>
> > Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx>
> > Subject: Re:  RBD Mirror DR Testing
> >
> > On Thu, Nov 21, 2019 at 8:29 AM Vikas Rana <vrana@xxxxxxxxxxxx> wrote:
> > >
> > > Hi all,
> > >
> > >
> > >
> > > We have a 200TB RBD image which we are replicating using RBD mirroring.
> > >
> > > We want to test the DR copy and make sure that we have a consistent copy in case primary site is lost.
> > >
> > >
> > >
> > > We did it previously and promoted the DR copy which broken the DR copy from primary and we have to resync the whole 200TB data.
> > >
> > >
> > >
> > > Is there any correct way of doing it so we don’t have to resync all 200TB again?
> >
> > Yes, create a snapshot on the primary site and let it propagate to the non-primary site. Then you can compare checksums at the snapshot w/o having to worry about the data changing. Once you have finished, delete the snapshot on the primary site and it will propagate over to the non-primary site.
> >
> > >
> > >
> > > Can we demote current primary and then promote the DR copy and test and then revert back? Will that require the complete 200TB sync?
> > >
> >
> > It's only the forced-promotion that causes split-brain. If you gracefully demote from site A and promote site B, and then demote site B and promote site A, that will not require a sync. However, again, it's probably just easier to use a snapshot.
> >
> > >
> > > Thanks in advance for your help and suggestions.
> > >
> > >
> > >
> > > Thanks,
> > >
> > > -Vikas
> > >
> > > _______________________________________________
> > > ceph-users mailing list
> > > ceph-users@xxxxxxxxxxxxxx
> > > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
> >
> >
> > --
> > Jason
> >
> >
>
>
> --
> Jason



-- 
Jason

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