On 2/27/07, Seth Price <[EMAIL PROTECTED]> wrote:

The numbers I'm getting:
4.00 KB per transfer
~750 transfers per second (trashing)
~3 MB per second
< 25% CPU utilization

The disk that is being used is a fairly recent SATA II disk. You can
immediately see from the numbers that something is very wrong with
the max throughput. I am guessing that the problem is in the transfer
size. Documentation that I read said that the rule of thumb is to
keep it below 200 transfers per second, and the block size is
normally closer to 128 KB.

While possible, I find it unlikely that the transfer size is the
problem here. More than likely it is disk seek bandwidth. Your SATA II
drive may be able to transfer 60MB/s when reading sequentially, but if
the head has to seek you're probably moving it around too much. I
would expect 100% CPU utilization (unless you have a
quad-core/CPU/thread machine) if the transfer size were the problem.
The only way to fix this is to get more spindles (i.e. RAID with
striping) or more RAM.

GNS
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