Specifications

7–32 CLI Commands
READ_CACHE (Default)
NOREAD_CACHE
Sets the controller’s cache read policy function. Read caching improves performance
in almost all situations. Therefore, it is recommended you leave its default setting,
READ_CACHE enabled. However, under certain conditions, such as when
performing a backup, read caching may not be necessary since only a small amount of
data is cached. In such instances, it may be beneficial to disable the read cache
function and remove the processing overhead associated with caching data.
READAHEAD_CACHE (Default)
NOREADAHEAD_CACHE
Enables the controller to keep track of read I/Os. If the controller detects sequential
read I/Os from the host, it will then try to keep ahead of the host by reading the next
sequential blocks of data (those the host has not yet requested) and put the data in
cache. This process is sometimes referred to as prefetch. The controller can detect
multiple sequential I/O requests across multiple units.
Read ahead caching improves host application performance since the data will be read
from the controller cache instead of disk. Read ahead caching is the default for units.
If you are adding a unit that is not expected to get sequential I/O requests, select
NOREADAHEAD_CACHE for the unit.
RUN (Default)
NORUN
Controls the unit’s availability to the host.
Specify RUN to make a unit available to the host.
Specify NORUN to make a unit unavailable to the host and to cause any data in cache
to be flushed to one or more drives. NORUN spins down all the disks used in the unit.
The drives making up the unit spin down after the data has been completely flushed.
NOTE: Do not specify the RUN and NORUN switches for partitions.