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Data on deleted BC/CA pairs

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Ninad_1
Honored Contributor

Data on deleted BC/CA pairs

Hi All,

Please can anyone tell me if I can delete BC/CA pairs and still have valid data on both the copies to be used independantly ?

Thanks,
Ninad
5 REPLIES
Ivan Ferreira
Honored Contributor

Re: Data on deleted BC/CA pairs

BC and CA are different.

In BC (local snapshot), if you create a clone, you can use independantly of the source, both have valid data.

If CA (remote copy), if you delete the association (Copy Set), you can use both vdisks with valid data independantly.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
SAKET_5
Honored Contributor

Re: Data on deleted BC/CA pairs

CA DR deletion leaves the source and the destination Vdisks intact, however please bear in mind that the destination Vdisk will have the "Write Protect" setting enabled. So, if you want to make it useful do clear this setting on your destination replica Vdisk.
Ninad_1
Honored Contributor

Re: Data on deleted BC/CA pairs

Ivan, Saket,

Thanks. Again in this post I forgot to mention that I have XP1024 arrays.
Sorry your replies say that BC can be used for local replication - that fine , but from your replies it is not clear that if I "delete" the pairs will the data be intact and can I use these volumes right away - without requiring any other re-configuration , basically these will have a database , so I want to know if I delete the BC pair will I still have valid databases on both copies which can be used by 2 different servers.

Thanks,
Ninad
Nigel Poulton
Respected Contributor
Solution

Re: Data on deleted BC/CA pairs

For the xp1024 -

BC - Deleting the pair will put both the P-VOL and S-VOL back into SMPL and the data on the S-VOL (backup caopy) will be consistent with how the P-VOL was when you deleted the pair. However, be careful when "deleting" (Pairsplit -S i think) BC pairs. BC pairs are never 100% in sync with each other. This is because updates from the P-VOL to the S-VOL are done asynchrounously meaning that your S-VOL will never be 100% in sync with your P-VOL. However, if you "split" your pairs and put them into PSUS the xp1024 will make sure that all pending updates from the P-VOL are copied to the S-VOL prior to splitting the pair.

So for BC my advice is ...... If you are splitting your pair you will be fine. To delete it I would recommend splitting it first and then deleting it. this way all pending updates will be copied to the S-VOL

For CA it also depends if you are doing CA synchronous or asychronous.

CA asynchronous is similar to what I said about BC. The updates are done asynchronously so you can never be sure your pairs are fully in sync with each other. Of course splitting them will make sure they are up to date before the split.

Even for CA synchronous I always split pairs before deleting them - even if I know that I/O to the P-VOL is stopped. Im just very careful with these types of operations.

So for CA my advice would be.....always split your pairs before deleting them.

Finally you may also need to tak into account consistency of data from the application point of view. Do you have to quiesce your application before performing a split!
Talk about the XP and EVA @ http://blog.nigelpoulton.com
Ninad_1
Honored Contributor

Re: Data on deleted BC/CA pairs

Thanks mackem.
Will request for any further queries after having a good thought on this.