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Old 12-27-2008, 03:25 PM
Moritz Muehlenhoff
 
Default Bug#441847: linux-image-2.6.21-2-486: poor via sata performance

On Tue, Sep 11, 2007 at 02:52:15PM +0000, Debian Live user wrote:
> Package: linux-image-2.6.21-2-486
> Version: 2.6.21-6
> Severity: normal
>
>
> I put several drives into a computer to zero them. With hdparm -t -T the
> sata drives appear to be the fastest but when writing urandom to all
> drives in parallel the order of speed observed is
> 1) USB2 fastest
> 2) IDE master (slightly slower than USB when the same drive connected)
> 3) IDE slave (slightly slower than master)
> 4) SATA ( *MUCH* slower than either IDE or USB although much faster
> drive connected)
>
> 11438284+0 records in
> 11438283+0 records out
> 5856400896 bytes (5.9 GB) copied, 5634.55 seconds, 1.0 MB/s
> 3815947+0 records in
> 3815947+0 records out
> 1953764864 bytes (2.0 GB) copied, 5634.55 seconds, 347 kB/s
> 14239665+0 records in
> 14239665+0 records out
> 7290708480 bytes (7.3 GB) copied, 5634.55 seconds, 1.3 MB/s
>
> The SATA drives below:
>
> 1032778+0 records in
> 1032777+0 records out
> 528781824 bytes (529 MB) copied, 5636.55 seconds, 93.8 kB/s
> 1030113+0 records in
> 1030113+0 records out
> 527417856 bytes (527 MB) copied, 5639.4 seconds, 93.5 kB/s
>
> Note that the SATA drives appear much faster when used separately. But
> when IO has to be scheduled to all drives they get the least throughput.

Does this behaviour still occur with more recent kernel versions?

Cheers,
Moritz




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