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Enabling DMA on Slackware [solved]


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Been trying to enable DMA on Slackware, and am having problems. For some reason, it just won't do it.

 

When I type the command to enable it, this is what I get:

 

root@slackware:/# hdparm -d1 /dev/hdc

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

 

This is the info output through hdparm for my drive:

 

root@slackware:/# hdparm -i /dev/hdc

/dev/hdc:

Model=Maxtor 6L080M0, FwRev=BANC1G10, SerialNo=L20Z3QPH
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=16
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes:  pio0 pio1 pio2 pio3 pio4
DMA modes:  mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2
AdvancedPM=yes: disabled (255) WriteCache=enabled
Drive conforms to: (null):

* signifies the current active mode

 

No mode seemed to be selected, so I tried the following command, as it recommended with the -d1 parameter to use -X with mdma2 or udma2 (I figured one of these since what is listed above).

 

I wasn't sure what to select, so tried using the following commands:

 

hdparm -d1 -X mdm2
hdparm -d1 -X udma2

 

when I then re-issued the hdparm -i command, it showed an asterisk against whichever option I chose, but DMA remained disabled.

 

I'm not sure what I need to do to enable it, or whether I actually need to or not. It's a new installation on this system, so can easily reinstall if it's needed. The hard disks are SATA based.

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The SATA drive is set to AUTO in the BIOS, and against DMA it says "Mode 5".

 

I'm wondering if this is why I have a problem. From my previous output it shows:

 

root@slackware:/# hdparm -i /dev/hdc

/dev/hdc:

Model=Maxtor 6L080M0, FwRev=BANC1G10, SerialNo=L20Z3QPH
Config={ Fixed }
RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4
BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=16
CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156301488
IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
PIO modes:  pio0 pio1 pio2 pio3 pio4
DMA modes:  mdma0 mdma1 mdma2
UDMA modes: udma0 udma1 udma2
AdvancedPM=yes: disabled (255) WriteCache=enabled
Drive conforms to: (null):

* signifies the current active mode

 

now if my BIOS is configured for Mode 5, does this mean my maximum based on the information above is Mode 2?!? I'm just guessing.....

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Yes, it is a 2.4.x kernel sata.i when I originally installed, and the drive is appearing as /dev/hdc.

 

I did try changing to User in BIOS and Mode 2, but this didn't make any difference. So what you mentioned above would explain not being able to enable DMA on this type of drive.

 

I'm going to reinstall with a 2.6.x kernel once I've found where it is on the 10.2 CD, and see if it'll be any better with this anyhow. Is there a reason as to why DMA can't be enabled on SATA drives? Will it not impact performance with it not enabled?

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I don't know exactly, why DMA does not work with SATA drives but actually, who cares? I have DMA disabled on one machine (AMD 1,2 GHz) as it was getting too unstable with DMA enabled and now, after several months, running without it, I can assure you that the "speed drop-off" is almost nonexistant. You hardly notice any changes.

Also: The 2.4 kernel in Slackware was rather painful for enabling DMA on my main machine, thus I installed the 2.6 kernel that comes on the CDs and it was 100% better imho. hdparm worked well with it.

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It's actually quite quick, so think everything must be running OK.

 

The installation at present is currently running a 2.4 kernel, but we're going to upgrade it shortly which should hopefully improve things further :P

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