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Parameter Description
• capable—The disk group and virtual disks are capable of
having security set, but security has not been enabled.
• enabled—The disk group and virtual disks have security
enabled.
dataAssurance
The setting to specify that a disk group, and the virtual disks
within the disk group, has data assurance protection to make
sure that the data maintains its integrity. When you use this
parameter, only protected physical disks can be used for the disk
group. These settings are valid:
• none - The disk group does not have data assurance
protection.
• enabled - The disk group has data assurance protection. The
disk group supports protected information and is formatted
with protection information enabled.
Additional Information
Cache Read Prefetch
The cacheReadPrefetch command lets the RAID controller module copy additional data blocks into
cache while the RAID controller module reads and copies data blocks that are requested by the host from
the physical disks into cache. This action increases the chance that a future request for data can be
fulfilled from cache. CacheReadPrefetch is important for multimedia applications that use sequential
data transfers. The configuration settings for the storage array that you use determine the number of
additional data blocks that the RAID controller module reads into cache. Valid values for the
cacheReadPrefetch parameter are TRUE or FALSE.
You do not need to enter a value for the cacheReadPrefetch parameter or the segmentSize
parameter. If you do not enter a value, the RAID controller module firmware uses the usageHint
parameter with fileSystem as the default value. Entering a value for the usageHint parameter and a
value for the cacheReadPrefetch parameter or a value for the segmentSize parameter does not
cause an error. The value that you enter for the cacheReadPrefetch parameter or the segmentSize
parameter takes priority over the value for the usageHint parameter.
Segment Size
The size of a segment determines how many data blocks that the RAID controller module writes on a
single physical disk in a virtual disk before writing data on the next physical disk. Each data block stores
512 bytes of data. A data block is the smallest unit of storage. The size of a segment determines how
many data blocks that it contains. For example, an 8 KB segment holds 16 data blocks. A 64 KB segment
holds 128 data blocks.
When you enter a value for the segment size, the value is checked against the supported values that are
provided by the RAID controller module at run time. If the value that you entered is not valid, the RAID
controller module returns a list of valid values. Using a single physical disk for a single request leaves
other physical disks available to simultaneously service other requests.
If the virtual disk is in an environment where a single user is transferring large units of data (such as
multimedia), performance is maximized when a single data transfer request is serviced with a single data
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