On Sat, 30 Sep 2006 at 8:56pm, Kirk Bocek wrote
3Ware's site advertises 300MB/Sec writes using 8 disks on the PCI Express
version of this card (the 9580 I think.) I'm guessing 4x PCI Express has more
bandwidth but 133Mhz 64-bit PCI-X is no slouch. The only two things I need to
change are to put the disks in 3GB/Sec SATA mode (they're in 1.5GB/Sec mode
right now) and to enable memory interleaving on the motherboard (I only have
two sticks of memory, this M/B needs 4 for interleaving.) But I don't think
these things should drop me down to the write performance of a single IDE
disk.
Does anyone have any suggestions on improving write performance?
1) Make sure the firmware on the board is up to date.
2) Turn off NCQ (last I knew, this was 3ware's advice).
3) Try putting the ext3 journal on another device.
4) Use XFS.
The last one is not just a prejudice. There really seems to be some sort
of odd (and rather bad) interaction between 3ware RAID5 and ext3. Going
to XFS really helps (especially with writes).
Oh, and be sure to 'blockdev --setra 16384' that device, which will help
with reads. 16384 is what works for me -- YMMV, of course.
--
Joshua Baker-LePain
Department of Biomedical Engineering
Duke University
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