Some queries regarding Snapshot XP

[Ninad_1]

Hi All,

Previously I had started a thread for some doubts on Snapshot XP and got some good help. Now after reading some more things on Snapshot XP I have some things not clear to me, and hence need your help.
1.In Snapshot XP which space will it use for writing to SVOLs and which space for storing snapshot data due to changes to PVOL ? Is it the same pool-VOL ?
2.Can Snapshot SVOL/VVOLs of different PVOLs use storage from same pool-VOL to store snapshot data?
3.If we use a BC PVOL/SVOL as Snapshot PVOL and when we are synchronising or refreshing the BC copy – will we still be able to access the Snapshot SVOLs ? Would there be a performance degradation if we do so ?
4.What does this statement mean (This is statement in "Snapshot XP user guide" on pg 51) - Using Snapshot XP, you cannot add new V-VOLs to the V-VOL group when creating V-VOLs. Ensure that you add enough V-VOLs to create the Snapshot XP pairs at this point.
5.After copying snapshot data using pairsplit - the SVOL becomes writable, now if any changes are made will they be overwritten on the snapshot data ? After these updates can we restore SVOL data onto PVOL - pairresync ...


Thanks a lot,
Ninad

[Ninad_1]

Any help please.

Regards,
Ninad

[Ninad_1]

Any help please :)
Does it mean that no one here has used Snapshot XP ? Any help from friends from HP here ?

Thanks,
Ninad

[avik]

hi
am not an xp guy but have a fair experience with hitachi storages, and words PVOL & SVOL sounds familiar to me.

i guess ur referrrig to the shadoimage of hitachi in here. shadowimage performas aninternal copy operations (with in the storage) for LUN pairs established by the user. Each shadowimage consists of one PVOL and upto 3 SVOL which are located in the same subsystem. Each SVOL must be paired with only one PVOL. during shadowimage operation the PVOL remain available to all hosts for read and write operations(except during reverse copy and quick restore). The SVOL become available for host acess only after the pair has been split

when shadowimage voume is created, the data on the PVOL is copied to the SVOL to sync the volums. During the initial copy and after the pair sync'd, all write operation to the SVOL are prohibhited. If you access an SVOL you can split the pair to make the SVOL accessible. While shadowimage pair is split, storage keeps a track of all changes to PVOL and SVOL. When you resync the pair, the differential data in the PVOL (due to PVOL and SVOL update) is copied to the SVOL so that the SVOL is again identical to the PVOL. for reverse copy, the differential data is in the SVOL is copied to the PVOL so that the PVOL is identical to the SVOL. There can be a performance degradation during the pairsync in progress. (SVOL are updated asynchronously)

[Ninad_1]

Thank you my friend, but I am not talking about BCV (thats what shadow image in HDS is ), but I am talking about Snapshot XP.
Isnt Peter Mattei there on the forums ? He has given me some very good advice on Snapshot earlier.

Hoping to hear from someone.

Thanks,
Ninad