[CentOS] DMA mode

David Mackintosh David.Mackintosh at xdroop.com
Mon Jun 2 15:22:29 UTC 2008


Hi folks,

I have an HP Proliant 140DL G2 server with what appears to be an IDE
drive in non-DMA mode.  Performance on the server is extremely bad
when large amounts of disk activity is taking place.

I think the problem is that my drive is not in DMA mode:

# hdparm /dev/hda

/dev/hda:
 multcount    = 16 (on)
 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 = 80026361856, start = 0

...but I can't set it on:

# hdparm -d1 /dev/hda

/dev/hda:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma    =  0 (off)

...which I think is because the IDE controller isn't really
recognized, or is pretending to be a SATA controller:

# lspci -v | less
00:1f.2 IDE interface: Intel Corporation 82801EB (ICH5) SATA Controller (rev 02) (prog-if 8a [Master SecP PriP])
        Subsystem: Hewlett-Packard Company: Unknown device 3208
        Flags: bus master, 66Mhz, medium devsel, latency 0, IRQ 193
        I/O ports at <unassigned>
        I/O ports at <unassigned>
        I/O ports at <unassigned>
        I/O ports at <unassigned>
        I/O ports at 1470 [size=16]

All the google hits I've seen so far imply I have to build a kernel module
but I'd rather not get into the business of rolling my own kernel if I
don't have to.

I spun through the HP support page for this box/OS combo, and I don't see
any SATA/IDE/ATA drivers, only SCSI/SAS drivers.

So before I continue on, can I get a sanity check here -- am I barking
up the right tree?

-- 
 /\oo/\
/ /()\ \ David Mackintosh | 
         dave at xdroop.com  | http://www.xdroop.com
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