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Old 12-11-2003, 10:25 AM   #1
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Wink DMA not enabled during linux startup

Hi everyone, I am running Debian at home. I have the 2.4.22 kernel. When linux is starting up I get a Warning message that says I do not have DMA turned on for my harddrive. I have tried hdparm -i /dev/sda and it tells me I have *udma5 as the default. If I see *udam5 does that mean I'm running in udma5 mode? There is no star on any of the dma options. Also, when I run hdparm -tT /dev/sda I get

Timing buffer-cache reads: 1800 MB/sec approximately
Timing buffered disk reads: 50 MB/sec approximately

Sorry I don't remember the values exactly and I only listed the per/sec values as I don't remember the others.

I have a Western Digital 8mb 80gig 7200 rpm drive, and a 2.6 800fsb p4. Are the hdparm values good, or am I running slow? I'm not sure. Also, when I do hdparm -I /dev/sda1 I'm told that dma is on = 1. This is surely confusing. Any help would be great. Sorry for any vagueness. I'll be more specfic once I get home. Debian is great!
Old 12-11-2003, 12:43 PM   #2
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here's a thread with various hdparm results listed that you can compare your numbers to:
Old 12-11-2003, 12:44 PM   #3
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hdparm -d /dev/xxx will tell you whether dma is enabled on that drive

hdparm -d1 /dev/xxx will enable it

there's also hdparm -c/c1 to detect enable/disable 32bit support

not to mention a few others
Old 12-11-2003, 01:31 PM   #4
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It don't mean squat. dma is enabled on the drive later in the boot process. If it wasn't you would never get 50MB/sec; you'd get more like 5MB/sec. I get the same warning on my debian install and I just ignore it. There are ways to enable dma earlier in the boot process which could result in faster boot times theoretically but I always figured it's not enabled by default for a reason so I never bothered to look into it.


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