Date: Fri, 29 Apr 2005 15:14:21 +0200 (CEST) From: kama <kama@pvp.se> To: Steven Hartland <killing@multiplay.co.uk> Cc: Petri Helenius <pete@he.iki.fi> Subject: Re: Very low disk performance Highpoint 1820a Message-ID: <20050429150534.L22614@ns1.as.pvp.se> In-Reply-To: <093701c54caa$303aac30$7f06000a@int.mediasurface.com> References: <20050428162201.39269.qmail@web41214.mail.yahoo.com><42711726.2000607@centtech.com><006201c54c46$14c0d290$b3db87d4@multiplay.co.uk> <093701c54caa$303aac30$7f06000a@int.mediasurface.com>
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On Fri, 29 Apr 2005, Steven Hartland wrote: > Just retried with a ~10Gb data set: > Write to FS: > dd if=/dev/zero of=.testfile bs=1m count=10000 > 10000+0 records in > 10000+0 records out > 10485760000 bytes transferred in 92.517222 secs (113338466 bytes/sec) > > Read from FS: > dd if=.testfile of=/dev/null bs=1m count=10000 > 10000+0 records in > 10000+0 records out > 10485760000 bytes transferred in 225.723348 secs (46454034 bytes/sec) > > Read from device: > dd if=/dev/da0 of=/dev/null bs=1m count=10000 > 10000+0 records in > 10000+0 records out > 10485760000 bytes transferred in 200.723666 secs (52239779 bytes/sec) > > N.B. didn't do the write to the device direct as the array is > the system drive so I don't think it would take kindly to that :) > > So it doesn't seem like caching is an issue and as others are seeing > similar performance issues on other RAID controllers is could well > not be a driver issue but I'm not ruling that out as yet as it could be > the same problem in each respective driver. > So far Highpoint 1820a and 3ware ?? ( Pete can u fill in the blank here ) > are exhibiting the same issue. > I have just tested on my system between 4.11 and 5.4. Both uses the same configuration on the write disk. its a RAID1+0 on Compaq SA6404 (ciss) running UFS1. The write to disk is similar on 4.11 and 5.4, but the read is 100% slower on 5.4 than 4.11. the R:W condition on 4.11 is 1:1 and on 5.4 2:1. I have tested this with dd and my own written disktest program. The results on both program is similar. so it isn't dev-null issues. I have tested with both 1GB files and 10GB files. 1GB files where really fast on reading, but i consider them false due to the RAID cache. Something is really wrong here... /Bjorn
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