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Compaq HSZ80 Array Controller ACS Version 8.3 Configuration and CLI Reference Guide
Initialize Switches
You can enable the following kinds of switches to affect the format of a disk drive or
storageset:
■ Chunk size (for stripesets and RAIDsets only)
■ Save configuration
■ Destroy/Nodestroy
After you initialize the storageset or disk drive, you cannot change these switches
without reinitializing the storageset or disk drive.
Chunk Size
Specify a chunk size to control the stripesize used for 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 d <
9, then chunk size =
256. If d > 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.
IMPORTANT: While a storageset may be initialized with a user-selected chunk
size, it is recommended that only the default value be used. The default value is
chosen to produce optimal performance for a wide variety of loads. The use of a
chunk size less than 128 blocks (64K) is strongly discouraged. There are
almost no customer loads for which small chunk sizes are of value and, in almost
all cases, selecting a small chunk size will severely degrade the performance of
the storageset and the controller as a whole. Use of a small chunk size on any
storageset can result in severe degradation of overall system performance.