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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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