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**Paul** · June 24th 14, 06:16 PM posted to alt.comp.hardware.pc-homebuilt

wrote:
While building some workstations with Centos operating system,
I found some Deskstar 320 GB PATA disks that were hardly used (about 30 hours).
I used these for swap and tmp, although swap shouldn't be used, as there is
heaps of RAM. I used SATA disks for root and home.
Now I find this Deskstar is very slow on one workstation.
Benchmark gives 4 MB/s read, when it should do about 100.
The Deskstar disk is 7200 RPM and supports UDMA6. The mainboard uses a Jmicron
chip for PATA, which also supports UDMA6. It is connected with
80-conductors cable. I swapped the Deskstar drive and the cable, and slowness
seems to be in the mainboard.
RHEL generic IDE driver is claimed to support the JMB368 since version 4.6,
and I have version 5.10.
hdparm shows the drive is running in UDMA5, which is ATA100 instead of
maximum ATA133, but is way faster than 4 MB/s
The SMART data shows no problems with the drives.

It does sound to me like PIO mode (4 to 7MB/sec), so you're
looking in the right area. You would think of
all utilities, hdparm would know what it was talking
about.

If there is a dmesg, see what happens to the drive when it
is detected, and whether any anomalies are noted.

Paul