HP StorageWorks HSG80 ACS Solution Software V8.8 for HP-UX Installation and Configuration Guide (AA-RV1FA-TE, March 2005)

Planning Storage Configurations
95HSG80 ACS Solution Software V8.8 for HP-UX Installation and Configuration Guide
Specifying Initialization Switches
Initialization switches set characteristics for established storagesets before they
are made into units. The following kinds of switches effect the format of a disk
drive or storageset:
■ Chunk Size (for stripesets and RAIDsets only)
■ Save Configuration
■ Destroy/Nodestroy
■ Geometry
Each of these switches is described in the following sections.
Note: After initializing the storageset or disk drive, you cannot change these switches
without reinitializing the storageset or disk drive.
Chunk Size
With ACS software, a parameter for chunk size (chunksize=default or n) on some
storagesets can be set. However, unit performance may be negatively impacted if
a non-default value is selected as the chunksize.
If a non-default chunk size has been calculated, verify that the chunk size value is
divisible by 8, with no remainder. If the value is not aligned with this rule, adjust
the chunk size value upward until it divisible by 8, with no remainder.
Specify the chunk size of the data to be stored to control the stripesize used in
RAIDsets and stripesets:
■ CHUNKSIZE=DEFAULT lets the controller set the chunk size based on the
number of disk drives (d) in a stripeset or RAIDset. If number of drives is less
or equal to 9, then chunk size = 256. If the number of drives is greater than 9,
then chunk size = 128.
■ CHUNKSIZE=n lets you specify a chunk size in blocks. The relationship
between chunk size and request size determines whether striping increases the
request rate or the data-transfer rate.