Expanding An Array; Adding Or Configuring Spare Drives - HP P600 User Manual

24 HP Smart Array P600 Controller User Guide
Accelerator ratio
The controller has an onboard cache called an Array Accelerator, which performs
both write-posting and read-ahead caching. The setting in CPQONLIN
determines the amount of memory allocated to the read and write caches.
For example, if the accelerator ratio is set to Read 75%:Write 25%, 75% of Array
Accelerator cache is dedicated to read-ahead cache and 25% is dedicated to the
write-posting cache. This option can be modified from the Controller Settings
menu.

Expanding an array

During an expand, performance may be slightly degraded. In most cases,
however, any potential degradation is offset by the addition of physical drives.
Some tips for expanding include:
•
Perform the expand process during periods of low server use. If you must
expand during peak periods, CPQONLIN enables you to set the priority of
the expand. Setting the priority to LOW affects performance the least, but it
takes longer for the new space to become available.
•
When expanding, always add drives with a capacity equal to or greater than
the capacity of the smallest drive in the array. Adding larger drives wastes
space because only the space that is equal to the smallest drive size can be
used.

Adding or configuring spare drives

When adding a spare drive to an array, an unassigned drive must exist or a drive
already assigned as a spare must exist on another array. You can assign a single
spare to any number of arrays or assign separate spares.
When you select Assign Spare Drive, only drives that qualify appear (for
example, only those spares that are large enough appear). If drives that you
expect to see do not appear, switch to the physical drive view (Tab key), and
check the size of the drives. The capacity of the spare must be equal to or greater
than the capacity of the smallest drive in the array.