Wednesday, May 08, 2002 10:31, Steve Lord [mailto:lord@xxxxxxx] wrote:
> However, the stripe width is truly more closely related to
> how many disks
> you have in a striped volume. Who knows what the DAC960 is
> really doing with
> that number. Most things though are based on stripe unit, and 8K does
> sound correct for that.
>
Thanks, Steve, for the info.
FYI, the manual for the controller defines the relevant terms as follows:
<Begin quote>
Segment Size (aka Cache Line Size)
The cache line size is defined as the size, in kilobytes (1024
bytes) of a single I/O operation. The Cache Line Size function is set in
conjuction with stripe size and represents the size of the data "chunk" that
will be read or written at one time.
Stripe Size
The size of a logically contiguous data block mapped to a single
disk. A stripe of data (data residing in actual physical disk sectors, which
are logically ordered first to last) is divided over all disks in the drive
group.
Stripe Width
The number of striped SCSI drives within a drive group.
<End quote>
All of this confirms your recommendation. So, is there an optimal size for
the stripe width given a "cache line size" and a number of disks. (On my
data drive, I have two disks, but since it is used for databases of 30Gb or
larger, I have set the stripe width to 1024k (the controller has a cache of
64M).
Thanks again for the help,
Murthy
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