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SPARCstorage Array Configuration Guide—March 1995
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RAID stripe sizes are adjustable to optimize for either random or sequential
I/O patterns.
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Striped data organizations (RAID 0, 0 + 1 and 5) can be tuned to optimize
for either random or sequential I/O performance.
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To optimize for random performance, striping is used to evenly balance the
I/O load across disk spindles in the RAID. This is done by setting the stripe
width as large or larger than the typical application I/O request. For
example, if the typical I/O request is 8 Kbytes, setting the stripe width to
64 Kbytes might be appropriate. This tends to evenly distribute I/O request
across all the disk drives in the RAID, and each I/O request is serviced by a
single disk drive.
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Sequential performance is optimized when data is spread out so that each
application I/O request spans all the drives in the RAID group. This
requires setting the stripe width so that it is small relative to the size of the
typical I/O request. For example, in a RAID group four data disks wide, if
typical application I/O size is 8 to 16 Kbytes, a stripe width of 2 Kbytes may
be best.