HP XP P9500 Storage - Manual (Page 22)

the I/O pattern to the secondary volumes, system option mode 787 may improve the response
performance.
Caution:
•
When you establish Compatible FlashCopy relationships with Preserve Mirror Compatible
FlashCopy function in COPY mode, a relationship in the MCU and a relationship in the RCU
are established, but a progress of a copy operation for a pair in the MCU and that in the RCU
are not synchronized. If you issue Withdraw during the copy operation, both copies of the
Compatible FlashCopy relationship are suspended. Therefore, the consistency of the data
between M-VOL and R-VOL is not ensured even though the Cnt Ac-S Z pair is in Duplex status.
This status is confirmed by the PPRC CQUERY command to a Cnt Ac-S Z volume or the Cnt
Ac-S Z Pair Operation window of Remote Web Console. To release this status, delete the Cnt
Ac-S Z pair.
•
If the relationship in the local site cannot be established, the relationship in the remote site
could be established, depending on the type of error. Even if you try again to create a
Compatible FlashCopy relationship using the Preserve Mirror Compatible FlashCopy function,
the relationship cannot be established in the local site. Release the relationship in the remote
site, and try again.
The following figures show the copying process of Compatible FlashCopy pairs and Cnt Ac-S Z
pairs with the Preserve Mirror Compatible FlashCopy function (shown using COPY mode).
Figure 15 The flow of Preserve Mirror Compatible FlashCopy function (COPY mode)
Preserve Mirror Compatible FlashCopy function starts to copy after the following:
•
The Cnt Ac-S Z M-VOL in DKC#1 becomes the Compatible FlashCopy S-VOL.
•
The Cnt Ac-S Z R-VOL in #2 becomes the Compatible FlashCopy S-VOL.
•
The Compatible FlashCopy relationship is established.
After the relationship is established, the Cnt Ac-S Z T-VOL in DKC#2 becomes the Compatible
FlashCopy S-VOL, and the Cnt Ac-S Z T-VOL in #2 becomes the Compatible FlashCopy T-VOL.
Data is copied in each Compatible FlashCopy pair, but not in the Cnt Ac-S Z pairs.If the Withdraw
command is issued to release the Compatible FlashCopy pair, M-VOL and R-VOL in Cnt Ac-S Z#2
becomes inconsistent.
22 About Compatible FlashCopy operations