On Mon, 29 Aug 2005, Mark Hahn wrote:
The U320 SCSI controller has a 64 bit PCI-X bus for itself, there is no other
device on that bus. Unfortunatly I was unable to determine at what speed
it is running, here the output from lspci -vv:
...
Status: Bus=2 Dev=4 Func=0 64bit+ 133MHz+ SCD- USC-, DC=simple,
the "133MHz+" is a good sign. OTOH the latency (72) seems rather low - my
understanding is that that would noticably limit the size of burst transfers.
I have tried with 128 and 144, but the transfer rate is only a little
bit higher barely measurable. Or what values should I try?
Version 1.03 ------Sequential Output------ --Sequential Input- --Random-
-Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks--
Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP
Raid0 (8 disk)15744M 54406 96 247419 90 100752 25 60266 98 226651 29 830.2 1
Raid0s(4 disk)15744M 54915 97 253642 89 73976 18 59445 97 198372 24 659.8 1
Raid0s(4 disk)15744M 54866 97 268361 95 72852 17 59165 97 187183 22 666.3 1
you're obviously saturating something already with 2 disks. did you play
with "blockdev --setra" setings?
Yes, I did play a little bit with it but this only changed read performance,
it made no measurable difference when writting.
Thanks,
Holger
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