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No DMA!

Discussion in 'General Discussion' started by sv1, Sep 28, 2007.

  1. sv1

    sv1 Well-Known Member

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    I noticed on our new machine that DMA was not enabled and when I tried to enable it via WHM it says that it has gone through the process yet it has not been enabled. When I run the script to enable it via shell I get:

    Code:
    
    [root@server scripts]# ./hdparamify
    /dev/hda:
     setting 32-bit IO_support flag to 1
     HDIO_SET_DMA failed: Operation not permitted
     IO_support   =  1 (32-bit)
    /dev/hdc:
     setting 32-bit IO_support flag to 1
     HDIO_SET_DMA failed: Operation not permitted
     IO_support   =  1 (32-bit)
    
    
    and here is more info:

    Code:
    
    [root@server] hdparm -d1 /dev/hda
    
    /dev/hda:
     setting using_dma to 1 (on)
     HDIO_SET_DMA failed: Operation not permitted
     using_dma    =  0 (off)
    
    Anyone know what's going on here? Thanks.
     
  2. nyjimbo

    nyjimbo Well-Known Member

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    Do you know if this drive can support DMA, what does the output from "dmesg" show ?. I am not familiar with setting DMA on in WHM, but I do know that some drives that can support DMA will not if your O/S cannot talk to the driver at a level to support it. Doesnt matter if its a new motherboard, some south bridge chip sets are just not supported and will fall back to PIO mode.
     
  3. tanfwc

    tanfwc Well-Known Member

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    Well, what is your interface of your harddisk? IDE or SATA?
     
  4. sv1

    sv1 Well-Known Member

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    dmesg =

    Code:
    http://www.pwrhost.com/pwrdma.txt
    
    sata
     
  5. tanfwc

    tanfwc Well-Known Member

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    As far as I know, DMA is not supported in SATA interface.

    correct me if i am wrong.
     
  6. philb

    philb Well-Known Member

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    I'm pretty sure tanfwc is correct; it's not necessary to set dma.

    hdparm -tT /dev/hda

    This will do a quick (safe) throughput test and should give you 45-65MB/sec or so for buffered disk reads (ignore cached reads figure in this instance) - the exact speed will vary depending on various factors (speed of disk, how well the chipset driver works, how busy the box is at the moment you run the test, etc etc etc).
     
  7. sv1

    sv1 Well-Known Member

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    Great, thanks!
     
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