Maximum Number Of Pairs Supported - Hitachi G200 User Manual

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• After you create a TC pair with DP-VOL whose size is larger than
4,194,304 MB (8,589,934,592 blocks), data management might fail due
to the insufficient pool capacity. In this case, all the P-VOL data is copied
to the S-VOL in units of tracks when you perform the TC pair resync
operation.
Note: If you enable Advanced System Settings No. 5 or No. 6 in Device
Manager - Storage Navigator, the differential data is managed by the pool to
which the TC pair volume is related even if the volume is smaller than
4,194,304 MB (8,589,934,592 blocks). This enables the total capacity of the
pair volumes to be increased over 1.8 PB. If you want the differential data to
be managed by the control memory again after you create pairs whose total
capacity is larger than 1.8 PB, you must reduce the total capacity of the pairs
that are smaller than 4,194,304 MB(8,589,934,592 blocks) to 1.8 PB by
deleting some pairs. When the differential data is managed by the control
memory, the total capacity of the TC, UR, and GAD pairs is 1.8 PB. For
example, if the total capacity of the TC pairs is already 1.8 PB, you cannot
create any UR or GAD pairs.

Maximum number of pairs supported

The maximum number of TrueCopy pairs is as follows:
• VSP G200: 2,048
• VSP G400, VSP G600, and VSP F400, F600: 4,096
• VSP G800 and VSP F800: 16,384
If CCI is used, a command device must be defined for each product;
therefore, the maximum number of pairs is as follows:
• VSP G200: 2,047
• VSP G400, G600 and VSP F400, F600: 4,095
• VSP G800 and VSP F800: 16,383
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Hitachi TrueCopy® User Guide for Hitachi Virtual Storage Platform Gx00 and Fx00 Models
Set system option mode 755 to OFF.
This action enables zero pages to be reclaimed.
Restore the blocked pool.
Release the V-VOL pages.
For Device Manager - Storage Navigator, use the Reclaim Zero
Pages window.
For CCI, use the raidcom modify ldev command.
You need to release differential data pages when you downgrade to
the firmware version that does not support TC pair creation with DP-
VOLs larger than 4,194,304 MB. The amount of time it takes to
release differential data pages depends on the number of specified
volumes, DP-VOL capacity, the number of allocated pages, and the
storage system's workload. It also depends on the type of storage
system. In some cases, it could take days to release all the differential
data pages.
Planning for TrueCopy