[Alug] Hard Drive performance Part 2

Steve Fosdick fozzy at pelvoux.demon.co.uk
Fri Sep 20 00:15:02 BST 2002


On Thu, 19 Sep 2002 23:42:05 +0100
Steve Fosdick <fozzy at pelvoux.demon.co.uk> wrote:

....

> The most likely of these if probably that the drive capability info says the drive doesn't support DMA so the next thing would be to find out where the IDE driver gets that from, whether it is from the drive itself or from the BIOS.

Further to my last message, I have found what appear to be the rules for whether Linux uses DMA automatically (i.e. without hdparm setting it on).

1.  If the drive model number is on the bad list then don't use DMA and don't check any further.  Drives on this list as of Kernel 2.4.19 are:

    WDC AC11000H
    WDC AC22100H
    WDC AC32500H
    WDC AC33100H
    WDC AC31600H
    WDC AC32100H
    WDC AC23200L
    Compaq CRD-8241B
    CRD-8400B
    CRD-8480B
    CRD-8480C
    CRD-8482B
    CRD-84
    SanDisk SDP3B
    SanDisk SDP3B-64
    SANYO CD-ROM CRD
    HITACHI CDR-8
    HITACHI CDR-8335
    HITACHI CDR-8435
    Toshiba CD-ROM XM-6202B
    CD-532E-A
    E-IDE CD-ROM CR-840
    CD-ROM Drive/F5A
    RICOH CD-R/RW MP7083A
    WPI CDD-820
    SAMSUNG CD-ROM SC-148C
    SAMSUNG CD-ROM SC-148F
    SAMSUNG CD-ROM SC
    SanDisk SDP3B-64
    SAMSUNG CD-ROM SN-124
    PLEXTOR CD-R PX-W8432T
    ATAPI CD-ROM DRIVE 40X MAXIMUM
    _NEC DV5800A

2. If the BIOS has enabled DMA on the drive then leave it on and set Linux to use it.

3. If the drive is a known good list then turn DMA on.  Drives on the good list are:

    Micropolis 2112A
    CONNER CTMA 4000
    CONNER CTT8000-A
    ST34342A

Steve.




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