HP StorageWorks XP Remote Web Console Software - Manual (Page 15)

Flex Copy XP user guide 15
• If you perform copy operations concurrently on two or more pairs, ensure that the pairs are located in
separate parity groups (that is, separate RAID groups). If two or more Flex Copy XP pairs are located
in the same parity group, host server I/O performance might decrease. HP recommends the following
remedies for reducing the risk of decreased I/O performance:
• Reduce the number of pairs in the parity group on which you will perform simultaneous copy
operations. For example, to create multiple pairs in one parity group, you should create one pair
after the copy operation on another pair finishes.
• Ensure that external array LUs mapped by External Storage XP are located in separate parity
groups.
• Add cache memory, disk adapters boards (DKAs), and parity groups if the local array is
overloaded. Host I/O performance might decrease if you use Flex Copy XP when the array is
overloaded.
• If the local array’s load increases, host server I/O performance (response) might be degraded. If Flex
Copy XP performs copy operations when the array’s load is heavy, it is more likely that host server
I/O performance (response) will degrade. The Copy Threshold option temporarily stops Flex Copy XP
copy operations when the array’s load is heavy. If you enable this option, you can minimize host I/O
performance degradation by temporarily stopping Flex Copy XP copy operations when the array’s
load is heavy.
For more information about the Copy Threshold option, contact your HP account support
representative.
NOTE: Copy operations stopped by the Copy Threshold option resume when the array’s load
decreases. If this option is enabled, copy operations for Flex Copy XP and for the following
products stop when the array’s load is heavy:
• Business Copy
• ShadowImage for z/OS
• Compatible Mirroring for IBM FlashCopy
• Compatible Mirroring for IBM FlashCopy Version 2
• Snapshot XP
• Auto LUN XP
• If you set an external array volume as a Flex Copy XP copy destination, the external array’s workload
increases because of the inflow of copy data. This means that Flex Copy XP processing might influence
host I/O performance for the copy destination external array.
Table 3 shows an estimate of Flex Copy XP’s copy speed. Review Table 3 , consider the workload that
Flex Copy XP imposes on the external array, and then execute Flex Copy XP operations.
NOTE: Copy speed might be slower than shown in Table 3 because of external factors (for
example, external array performance, drive status, and host I/O).
• Flex Copy XP enables up to 32 concurrent copy operations. If the number of copy requests exceeds 32,
the 33rd and subsequent requests are not processed until a running copy operation finishes.
Table 3 Estimate of Flex Copy XP’s copy speed
Number of pairs for which Flex
Copy XP copy processing is in
progress
Maximum copy speed per pair
(MB/s)
Maximum copy speed for the
whole array (MB/s)
1 60 60
2 55 110
8 20 160
16 or more 10 or less 160