Hdparm

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hdparm is used in Linux for setting harddisk options.

To view current settings, simply run: hdparm /dev/hda (or /hdb, /hdc, etc.)

-c1 enables 32-bit I/O

-d1 enables DMA

-X66 enables ATA/33

PIO mode Switch Burst Rate
0 -X08 3.3MB/sec
1 -X09 5.2MB/sec
2 -X10 8.3MB/sec
3 -X11 11.1MB/sec
4 -X12 16.7MB/sec


MW DMA mode Switch Burst Rate
0 -X32 4.2MB/sec
1 -X33 13.3MB/sec
2 -X34 16.6MB/sec
UDMA mode Switch Burst Rate
2 (ATA/33) -X66 33MB/sec
4 (ATA/66) -X68 66MB/sec
5 (ATA/100) -X69 100MB/sec

Red Hat uses /etc/rc.sysinit to call scripts /etc/sysconfig/harddiskhda, /etc/sysconfig/harddiskhdb, etc. to run hdparm upon boot.

File: /etc/sysconfig/harddiskhda:

USE_DMA=1

EIDE_32BIT=1

To enable DMA during boot, add the following line to your lilo.conf file:

append = "ide0=dma"