HP XP Auto LUN Software - Manual (Page 22)

22 Auto LUN XP for the XP12000/XP10000
The following table shows the number of control cylinders according to the emulation type.
Auto migration planning
Auto LUN XP will not plan an auto migration when:
• There is no reserve volume with the same emulation type and capacity as the source volume in the
same or next higher/lower HDD class (auto migration is performed only between consecutive classes or
within the same class)
• Auto LUN XP cannot estimate the usage rate for the target parity group because of some condition (for
example, invalid monitor data)
• The estimated usage of the target parity group or volume is over the user-specified maximum disk usage
value for that HDD class
• The estimated performance improvement is not large enough
Auto migration execution
Auto LUN XP will not execute an auto migration operation when:
• The current usage (last 15 minutes) of the source or target parity group or volume is over the maximum
disk usage rate for auto migration
• The current write pending rate for the disk array is 60% or higher
Manual migration execution
Auto LUN XP will execute a manual migration operation when the current write pending rate for the disk
array is 60% or higher.
Copy Threshold option
If Auto LUN XP performs migration 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 Auto LUN XP 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.
CAUTION: A volume migration operation might fail if hosts frequently update the volumes being
migrated. If you enable Copy Threshold, Auto LUN XP temporarily stops copy processing when the disk
array is overloaded, which increases the possibility of a failed volume migration operation. Using the
Copy Threshold operation is not recommended when hosts frequently update the volumes being migrated.
IMPORTANT: Contact your HP support account representative for more information about the Copy
Threshold option.
In addition to Auto LUN XP operations, Copy Threshold temporarily stops copy operations for the following
applications when the disk array workload is heavy:
Table 7 Control cylinders by emulation type
Emulation type Number of control cylinders
OPEN-3 8 (5,760KB)
OPEN-8 27 (19,440KB)
OPEN-9
OPEN-E 19 (13,680KB)
OPEN-L 7 (5,040KB)
OPEN-V 0 (0KB)