HP XP P9500 Storage - Manual (Page 58)

Suspend pairs
You can suspend a pair, which suspends data copying to the R-VOL. The following takes place
when a pair is suspended:
•
I/O writes from the host continue to the M-VOL, but stop to the R-VOL.
•
Any current update copy operation completes to the R-VOL, ensuring data consistency to the
point of the suspend operation.
•
Pair status changes to suspended-delete pair to RCU.
•
The main system records the updated tracks to the M-VOL that occur after pair suspension as
differential data. This data is copied to the R-VOL when the pair is resynchronized.
•
You can set an option to block updates to the M-VOL while the pair is suspended. This results
in the M-VOL and R-VOL staying synchronized.
•
Another option is to enable I/O to the R-VOL from a host. The remote system records the
updated tracks as differential data. When the pair is resynchronized, the remote system sends
the differential data to the main system, which merges all differential data to determine which
tracks are out-of-sync.
Prerequisite information
•
The pair must be in Pending or Duplex status.
Procedure 6 To suspend one or more pairs
1. On the menu bar, click Actions > Remote Copy > Continuous Access Synchronous for Mainframe
> Pair Operation. The Pair Operation window opens.
2. Change to Modify mode by clicking the icon.
3. In the tree, select CU or the CU grouping where the pair is located.
4. In the volume list, select the Continuous Access Synchronous Z pair(s) that you want to suspend.
5. Right-click, and select Suspend Pair from the menu. The Suspend Pair dialog box displays.
6. Select a option from the SSB [F/M=FB] list.
When this option is enabled (and PPRC Support = Yes), the MCU will notify all attached hosts
(IEA494I message) that the pair was suspended. This option should always be enabled.
If PPRC support = No, the x’FB’ sense information will not be reported to the host, even if the
SSB (F/M = FB) suspend option is enabled.
Do not use the M-VOL failure suspend kind option if the M-VOL is required for system operation.
Make sure to use the R-VOL suspend kind option, so that the M-VOL continues accepting I/Os.
7. From the Suspend Kind list, select one of the following:
•
R-VOL (default). The M-VOL accepts host write I/O (though still adheres to the fence level
in failure conditions).
This setting should be used when you need to keep the M-VOL online.
•
M-VOL Failure. The main system will reject host write I/O to the M-VOL while the pair is
suspended, regardless of fence level.
Use this option when you need to maintain synchronization of the pair while it is
suspended. Do not use this option if the M-VOL is required for system operation.
8. Click Set then Apply.
If the operation does not start normally, an error code displays in the Error Code column in the
Preview list. To display an error message, select the LDEV, right-click, and select Error Detail.
58 Pair operations