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SubjectRe: Dog slow IDE
Hi Tony,

Just a me too earlier today with 2.4.19-pre2-ac4, on a dual celeron
440BX-based system.

Im my case, I have 3 hdds in a raid-5, hda, hdb, and hdc.

hda and hdb were both performing as expected 18-22MB/sec. hdc was
down at the 1.8-2.2MB/sec - even after trying to use hdparm to reset
the drive transfer rates (-p, -d1 -X66, -d0 -X12 (to try pio) etc).

None of the attempts using hdparm altered the hdc transfer rate in any
noticable fashion. I powered down the machine, and on reboot, the hdc
transfer rate returned to the expected range 18-22MB/sec), and the
raid performance went up to it's usual level from the 5MB/sec it was

I couldn't see any reason for the odd behaviour, and I had put it down
to 'just one of those things' as the 3 or 4 test reboots since haven't
produced the strangely low-transfer rate again.



On Mon, 11 Mar 2002, Tony Hoyle wrote:

> For some reason the my IDE is running extremely slow (which accounts for
> why this box feels so sluggish).


> However:
> /dev/hda:
> Timing buffered disk reads: 64 MB in 16.27 seconds = 3.93 MB/sec
> /dev/hdb:
> Timing buffered disk reads: 64 MB in 32.99 seconds = 1.94 MB/sec
> 1.94MB/sec is *way* to slow for a UDMA5 hard disk surely?

Yes. On another system, I pull 35-40MB/sec off each individual
barracuda IV drive, and 50+ from the combined raid array (I assume PCI
bandwidth limited, as twiddling BIOS PCI settings boosted this from 41
to 50).



Mark Cooke The views expressed above are mine and are not
Systems Programmer necessarily representative of university policy
University Of Birmingham URL:

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