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Re-synching Filers after a site failover scenario


One of our customers has asked about re-synching Filers after a site failover scenario. Is it correct that if site A has failed over to site B, eg link dead, and site B is made read/write, and promoted to primary for a period of time, once the link is re-established, do we need to do a full baseline copy of all the data from site B back to site A? Or just the deltas that have been written to B during the outage period?

I did think that as long as both sites have the same last snapmirror snapshot present, it would just require a snapmirror update and site B to send back the deltas/snapshots taken during the outage period? But if the last snapmirror snapshot has been deleted from site B, or overwritten, depending how long the outage was for, would that require a full baseline copy back to A (maybe using an NDMP tape to ship back to A and re-seed locally??)

If you could shed some light on this, that would be much appreciated!


Re: Re-synching Filers after a site failover scenario

You are correct.  As long as you have a common snapshot between the 2 volumes then you can "snapmirror resync" back to production.  Without a common snapshot you need to re-baseline.  If you are going to seed with tape, use snapmirror to tape.