Optimizing Performance - HP Surestore Disk Array 12h - And FC60 Service Manual

Optimizing Performance

Disk array performance is influenced by many factors, some host-related, some related to the configuration
of the disk array itself. Host-related disk array performance issues can typically be identified and corrected
using operating system utilities or third-party applications designed for this purpose.
The following list identifies some of the factors that directly influence disk array performance. Other
factors, such as a rebuild, can temporarily affect array performance.
Amount of available RAID 0/1 – In most cases, the more RAID 0/1 space available, the better the
disk array performance. With enough RAID 0/1 space, the disk array can service all write I/Os from
RAID 0/1, thus allowing an optimum write working set. RAID 0/1 space can be increased by
increasing the amount of unallocated capacity on the disk array.
Enabling Active Hot Spare – With Active Hot Spare enabled, the disk array can recover quickly from
a disk failure without the need for any action on your part. This maintains performance because while
the disk array is operating in non-redundant or critical mode, performance decreases. Active Hot Spare
provides an additional performance benefit because it is used as RAID 0/1 space until a disk fails.
Amount of cache DRAM – Increasing the amount of cache DRAM can alleviate bottlenecks that may
form in the controller data path. This increases the rate at which the disk array can service host I/Os.
Proper disk module installation – Installing the disk modules in the correct slots in the enclosure
distributes the disks across the internal SCSI busses and balances the I/O load properly. Disk modules
should be installed from left-to-right, top-to-bottom.
Keep the disk capacity small – Having twelve disks with smaller capacities will improve the
performance as compared to having twelve disks with larger capacities.
Concepts and Management
Optimizing Performance
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