On Sun, Jan 28, 2007 at 11:28:27AM -0800, Joe wrote:
> Some more tests:
>
> # dd if=/dev/zero of=./testfile count=1000000
> 1000000+0 records in
> 1000000+0 records out
> 512000000 bytes transferred in 16.354 secs (31306797 bytes/sec)
>
> # dd if=./testfile of=/dev/null count=1000000
>
> 1000000+0 records in
> 1000000+0 records out
> 512000000 bytes transferred in 6.013 secs (85137347 bytes/sec)
>
> So is 30MBps acceptable write speed for RAID 5 on a Compaq Smart Array
> 64xx controller?
>
> Could this be a driver issue?
I doubt it: clearly it can transfer data at 85MBps, and it's unlikely that
the SCSI bus can transfer data faster in one direction than the other.
I don't know this controller specifically, but maybe a better controller
would give you better RAID5 write performance. Or maybe something isn't
quite set up correctly on the card (e.g. if there's NVRAM write-through
cache, maybe the battery isn't present or it's disabled for some other
reason)
> I have another box with the same controller, but in 2 disks in RAID 0.
>
>
> # bioctl -h ciss0
> Volume Status Size Device
> ciss0 0 Online 136G sd0 RAID0
> 0 Online 67.8G 0:0.0 noencl <COMPAQ BD0728A4B4
> 1 Online 67.8G 0:1.0 noencl <COMPAQ BD0728A4B4
>
>
> # dd if=/dev/zero of=/nsm/testfile count=20000 bs=128k
> 20000+0 records in
> 20000+0 records out
> 2621440000 bytes transferred in 29.696 secs (88274982 bytes/sec)
RAID 0 is just striping, so half the data gets written to one disk while
half gets written to the other, so that would be expected to have better
performance than a single disk.
Regards,
Brian.
