Copy Threshold Option; Cascade Pairs; Bc Software On The Command View Xp Management Station - HP StorageWorks XP10000 User Manual

S-VOL updates) is copied to the S-VOL, so the S-VOL is again identical to the P-VOL. For reverse resync, the
differential data in the S-VOL (due to P-VOL and S-VOL updates) is copied to the P-VOL, so the P-VOL is now
identical to the S-VOL.
NOTE: BC S-VOLs are updated asynchronously. For a volume pair with PAIR status, the P-VOL and S-VOL
may not be identical. For further information on BC update copy operations, see
page 21.
BC P-VOLs or S-VOLs should not be concentrated in the same RAID group. To disperse workloads of RAID
groups, each RAID group should have both P-VOLs and S-VOLs evenly distributed. BC pairs for which BC
operations are performed simultaneously should be in different RAID groups. If BC pairs are concentrated
in only a few RAID groups, host I/O performance may be degraded.
If the disk array is overloaded, increase cache, disk adapters, and/or RAID groups. Consider assigning
BC S-VOLs in newly installed RAID groups. If you continue BC operations with an overloaded disk array,
host I/O performance may be degraded.

Copy Threshold option

If BC performs copy operations when the disk array workload is heavy, host server I/O performance might
be degraded. To minimize this performance degradation, enable Copy Threshold, which temporarily stops
all BC copy operations when the disk array has a heavy workload. Copy operations that are stopped by
the Copy Threshold option resume when the disk array workload is lighter.
This option is different from the Host I/O Performance option
page 31), because it is effective only when the disk array workload is heavy.
NOTE: Contact your HP support account representative for more information about the Copy Threshold
option.
In addition to BC operations, Copy Threshold temporarily stops copy operations for the following
applications when the disk array workload is heavy:
• Auto LUN XP
• ShadowImage for z/OS
• Hitachi FlashCopy Mirroring
• Hitachi FlashCopy Mirroring Version 2
• Snapshot XP
• Flex Copy XP

Cascade pairs

The BC cascade function adds a second layer of pairs onto the first layer of original BC pairs. Use these
two layers of pairs (L1 and L2) to create and maintain up to nine copies of one original BC primary volume
(P-VOL). See "Cascade

BC software on the Command View XP management station

When installed on the Command View XP management station, the BC software displays BC information
and performs BC operations. The Command View XP management station can be attached to multiple disk
arrays. The Command View XP management station acquires status from and issues commands to BC
P-VOLs and S-VOLs.
function" on page 31 for further information on the cascade function.
("Host I/O Performance
Business Copy XP user guide for the XP10000/XP12000
"Paircreate operation" on
option" on
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