HP Surestore Disk Array 12h - And FC60 System Administrator Manual page 120

Managing the HP SureStore E Disk Array 12H on MPE
Tips for Configuring the Disk Array On MPE
Configuration
Option
Number of disk
drives
Unallocated disk
array capacity
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Impact on Performance and Capacity
Performance. Increase the number of disk mechanisms in the disk array
for maximum performance. As the number of individual disks is
increased, the number of potential I/Os that can be performed
simultaneously increases as well. This will improve performance in
environments that place heavy I/O demand on the disk array.
Capacity. The capacity of a disk array that is fully populated with disk
mechanisms can only be increased by replacing lower capacity disks with
higher capacity disks.
Performance. Unallocated capacity is used as additional RAID 0/1
space. The amount of RAID 0/1 space required to maintain optimal
performance is determined by the write working set parameter.
Capacity. To create the maximum amount of storage capacity, allocate
all available capacity to LUNs.