Alan Hodgson schrieb:
>>>>> Mario Weilguni <mweilguni@sime.com> wrote:
>>>>>
>>> strange values. An individual drive is capable of delivering 91
>>> MB/sec
>>>
>>> sequential read performance, and we get values ~102MB/sec out of a
>>> 8-drive RAID5, seems to be ridiculous slow.
>>>
>
>
> What command are you using to test the reads?
>
> Some recommendations to try:
>
> 1) /sbin/blockdev --setra 2048 device (where device is the partition or LVM
> volume)
>
> 2) Use XFS, and make sure your stripe settings match the RAID.
>
> Having said that, 102MB/sec sounds really low for any modern controller with
> 8 drives, regardless of tuning or filesystem choice.
>
>
First, thanks alot for this and all the other answers.
I measured the raw device performance:
dd if=/dev/cciss/c0d0 bs=64k count=100000 of=/dev/null
I get poor performance when all 8 drives are configured as one, large
RAID-5, and slightly poorer performance when configured as JBOD. In
production, we use XFS as FS, but I doubt this has anything to do with
FS tuning.