On Tue, May 7, 2024 at 7:54 AM Eugen Block <eblock@xxxxxx> wrote: > > Hi, > > I'm not the biggest rbd-mirror expert. > As understand it, if you use one-way mirroring you can failover to the > remote site, continue to work there but there's no failover back to > primary site. You would need to stop client IO on DR, demote the image > and then import the remote images back to primary site. Once > everything is good you can promote the image on primary again. The > rbd-mirror will then most likely be in a split-brain situation, which > can be resolved by resyncing images from primary again. You can't do a > resync on primary site because there's no rbd-mirror daemon running. > > Having two-way mirroring could help, I believe. Let's say you lose the > primary site, you can (force) promote images on the remote site, > continue working. Once the primary site is back up (but not primary > yet), you can do the image resync from the remote (currently primary) > site (because there's a rbd-mirror daemon running on the primary site > as well). Once the primary site has all images promoted, you'll > probably have to resync on the remote site again to get out of the > split-brain. Also, you need to demote the out-of-date images in the cluster that came back, before issuing resync on them. This is to resolve the split-brain. See, https://docs.ceph.com/en/latest/rbd/rbd-mirroring/#force-image-resync -Ramana > But at least you won't need to export/import images. > > But you'll need to test this properly to find out if your requirements > are met. > > Regards, > Eugen > > > Zitat von V A Prabha <prabhav@xxxxxxx>: > > > Dear Eugen, > > We have a scenario of DC and DR replication, and planned to explore RBD > > mirroring with both Journaling and Snapshot mechanism. > > I have a 5 TB storage at Primary DC and 5 TB storage at DR site with > > 2 different > > ceph clusters configured. > > > > Please clarify the following queries > > > > 1. With One way mirroring, the failover works fine in both journaling and > > snapshot mechanism and we are able to promote the workload from DR site. How > > does Failback work? We wanted to move the contents from DR to DC but > > it fails. > > In journaling mechanism, it deletes the entire volume and recreates it afresh > > which does not solve our problem. > > 2. How does incremental replication work from DR to DC? > > 3. Does Two-way mirroring help this situation. According to me, in > > this method, > > it is for 2 different clouds with 2 different storages and > > replicating both the > > clouds workloads? Does Failback work in this scenario ? > > Please help us / guide us to deploy this solution > > > > Regards > > V.A.Prabha > > > > > > Thanks & Regards, > > Ms V A Prabha / श्रीमती प्रभा वी ए > > Joint Director / संयुक्त निदेशक > > Centre for Development of Advanced Computing(C-DAC) / प्रगत संगणन विकास > > केन्द्र(सी-डैक) > > Tidel Park”, 8th Floor, “D” Block, (North &South) / “टाइडल पार्क”,8वीं मंजिल, > > “डी” ब्लॉक, (उत्तर और दक्षिण) > > No.4, Rajiv Gandhi Salai / नं.4, राजीव गांधी सलाई > > Taramani / तारामणि > > Chennai / चेन्नई – 600113 > > Ph.No.:044-22542226/27 > > Fax No.: 044-22542294 > > ------------------------------------------------------------------------------------------------------------ > > [ C-DAC is on Social-Media too. Kindly follow us at: > > Facebook: https://www.facebook.com/CDACINDIA & Twitter: @cdacindia ] > > > > This e-mail is for the sole use of the intended recipient(s) and may > > contain confidential and privileged information. If you are not the > > intended recipient, please contact the sender by reply e-mail and destroy > > all copies and the original message. Any unauthorized review, use, > > disclosure, dissemination, forwarding, printing or copying of this email > > is strictly prohibited and appropriate legal action will be taken. > > ------------------------------------------------------------------------------------------------------------ > > > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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