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.
