Jesse Keating wrote:
On Thu, 2005-04-28 at 10:49 -0600, jeff wrote:
>Do either of these versions address the "Extremely high iowait with
>3Ware array and moderate disk activity" bug? It's been open for just
>over a year & has 259 comments.
>I can confirm this bug with v2.26.02.001, fwiw.
Most likely not as much as you'd like. That unfortunately is an
artifact of 3ware's design. We never use these systems for high usage
scenarios like a database server or sometimes even a home directory
server. Nearline backup and slow storage is what we consider them
useful for. The '9.2' release does have significant performance
increases (firmware and driver need to be updated) but I don't think
they'll solve the IO Wait state any time soon.
I can't benchmark it since it's a live system, but the following helped
with the iowait problem under FC2:
echo 512 > /sys/block/sda/queue/nr_requests
It was suggested on LKML that nr_requests be double queue_depth. I get
much more even performance now. It no longer bogs down & goes out to
lunch when I throw a DVD ISO at it, for example.
I also use:
blockdev --setra 16384 /dev/sda