On Fri, Nov 22, 2019 at 11:16 AM Vikas Rana <vrana@xxxxxxxxxxxx> wrote: > > Hi All, > > We have a XFS filesystems on Prod side and when we trying to mount the DR copy, we get superblock error > > root@:~# rbd-nbd map nfs/dir > /dev/nbd0 > root@:~# mount /dev/nbd0 /mnt > mount: /dev/nbd0: can't read superblock Doesn't look like you are mapping at a snapshot. > > Any suggestions to test the DR copy any other way or if I'm doing something wrong? > > Thanks, > -Vikas > > -----Original Message----- > From: Jason Dillaman <jdillama@xxxxxxxxxx> > Sent: Thursday, November 21, 2019 10:24 AM > To: Vikas Rana <vrana@xxxxxxxxxxxx> > Cc: dillaman <dillaman@xxxxxxxxxx>; ceph-users <ceph-users@xxxxxxxxxxxxxx> > Subject: Re: RBD Mirror DR Testing > > On Thu, Nov 21, 2019 at 10:16 AM Vikas Rana <vrana@xxxxxxxxxxxx> wrote: > > > > Thanks Jason. > > We are just mounting and verifying the directory structure and make sure it looks good. > > > > My understanding was, in 12.2.10, we can't mount the DR snapshot as the RBD image is non-primary. Is this wrong? > > You have always been able to access non-primary images for read-only operations (only writes are prevented): > > $ rbd info test > rbd image 'test': > <... snip ...> > mirroring primary: false > > $ rbd device --device-type nbd map test@1 > /dev/nbd0 > $ mount /dev/nbd0 /mnt/ > mount: /mnt: WARNING: device write-protected, mounted read-only. > $ ll /mnt/ > total 0 > -rw-r--r--. 1 root root 0 Nov 21 10:20 hello.world > > > Thanks, > > -Vikas > > > > -----Original Message----- > > From: Jason Dillaman <jdillama@xxxxxxxxxx> > > Sent: Thursday, November 21, 2019 9:58 AM > > To: Vikas Rana <vrana@xxxxxxxxxxxx> > > Cc: ceph-users <ceph-users@xxxxxxxxxxxxxx> > > Subject: Re: RBD Mirror DR Testing > > > > 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 > > > > > > > -- > Jason > > -- Jason _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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