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SubjectRe: RAID 5 performance problems
Stephan,

> here benchmark from my system with an fasttrak-tx4 (same card jonathan
> has) with WD1800BB :

The WD1800BB and the WD1200BB use the same technology (same data density,
fewer platters). The streaming speed should be very similar.

> /dev/hde:
> Timing buffer-cache reads: 128 MB in 0.28 seconds =457.14 MB/sec
> Timing buffered disk reads: 64 MB in 1.37 seconds = 46.72 MB/sec
>
> WD1800BB on onboard ultra100 controller :
>
> /dev/hdo:
> Timing buffer-cache reads: 128 MB in 0.28 seconds =457.14 MB/sec
> Timing buffered disk reads: 64 MB in 1.58 seconds = 40.51 MB/sec
>
> WD1800BB on onboard ultra33 controller :
>
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.28 seconds =457.14 MB/sec
> Timing buffered disk reads: 64 MB in 2.55 seconds = 25.10 MB/sec

OK. We've found a potential issue. Are the disks being identified as
UDMA-33 or UDMA-66/100/133? The performance numbers agree too closely for
this to be a coincidence. Check the boot logs.

Good luck.
Peter Ashford

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