Awful hard drive performance

I have a box running Slackware 11 with a 2.6.19.1 kernel. This box
has two IDE disks, which at boot time are detected as follows:

Probing IDE interface ide0...
hda: SAMSUNG SP0802N, ATA DISK drive
hdb: WDC WD1200JB-00EVA0, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
Probing IDE interface ide1...
Probing IDE interface ide1...
hda: max request size: 512KiB
hda: 156368016 sectors (80060 MB) w/2048KiB Cache, CHS=16383/255/63, UDMA
(100)
hda: cache flushes supported
hda: hda1 hda2 hda3 hda4 < hda5 hda6 >
hdb: max request size: 512KiB
hdb: 234441648 sectors (120034 MB) w/8192KiB Cache, CHS=16383/255/63, UDMA
(100)
hdb: cache flushes supported
hdb: hdb1

With more detail, the lshw application returns this information:

*-disk:0
description: ATA Disk
product: SAMSUNG SP0802N
physical id: 0
bus info: ide@xxx
logical name: /dev/hda
version: TK200-04
serial: S00JJ40Y284813
size: 74GB
capacity: 74GB
capabilities: ata dma lba iordy smart security pm partitioned
partitioned:dos
configuration: mode=udma5 smart=on

*-disk:1
description: ATA Disk
product:WDCWD1200JB-
00EVA0
vendor: Western
Digital
physical id: 1
bus info:
ide@xxx
logical name: /dev/hdb
version:
15.05R15
serial: WD-WMAEK2624312
size:
111GB
capacity:
111GB
capabilities: ata dma lba iordy smart security pm partitioned
partitio
ned:dos
configuration: mode=udma5
smart=on

When I run the hdparm command on them (either of them) this is what I get:

/dev/hda:
multcount = 0
(off)
IO_support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 0 (off)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 256 (on)
geometry = 16383/255/63, sectors = 234441648, start = 0

The problem is, when I try to enable DMA on these drives by means
of hdparm -d, using_dma remains off. Anybody can offer an explanation as
to why? I understand this must be turned on in order to have decent disk
performance. In fact, I noticed that when transferring big files from this
box to other boxes in my LAN via SCP, instead of attaining the roughly
8-10 MBs expected, the transfer rate never goes above 2.3 MBs. I wonder
if this is the reason why?
.

Relevant Pages

  • Re: Awful hard drive performance
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    (comp.os.linux.misc)
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