XP business copy "quick split" question.

[Peter Mattei]

In addition I want to come back to one of your initial questions:

Guiseppe: The question is: where the storage writes the delta tracks that are not sync ? How the S-VOL take the data from P-VOL, during the background process ? There is something like journal, pherhaps ? Somewhere, I have to write the delta tracks that are not sync when I create the at-time BC, it's right ?? And from performance side, how much it impacts on P-VOL or cache ??

Pete: Each BC vol has a track map in Shared Memory where the XP records track changes.
When you split a pair a differential bitmap is created.

- If you update a track on the P-vol before the track has been copied to the S-vol the XP will first copy the track to the S-vol and then update the track on the P-vol.

- If you read a track from the S-vol that has not been copied it will be read from the P-vol.
You see, the XP can perfectly handle this.

These processes of course do have some performance impact. But since most BC tasks are performed asynchronously in the background they do usually not hurt that much.

Cheers
Pete

[giuseppe monardo]

We have XP24000 and P9500

I don't understand very much, maybe we have not centered my "FOCUS".

I just would like to understand if it's possible to do a QUICK PAIRRESYNC and if QUICK PAIRRESYNC is consistent (in other words, if P-VOL and S-VOL are consistent immediately after the quick pairresync, obviously when P-VOL and S-VOL are in PAIR state).
If I understood correctly from hitachi forum, for example, the storage shows me PAIR STATE faster than normal pairresync operation, but I see that it's a "fake" status, infact P-VOL and S-VOL are still in copy in backgroung.

What do you think about this ?

Thanks a lot in advance