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Disk hdc3 (/) No DMA! (Click to Enable)

Discussion in 'General Discussion' started by SupermanInNY, Jan 14, 2005.

  1. SupermanInNY

    SupermanInNY Well-Known Member

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    Hi Y'all,

    I just upgraded the kernel to 2.4.28.
    I noticed that the

    Main >> Server Status >> Service Status

    Now shows my various partitions (which reside on the same HD) as NO DMA and allow
    the Click to Enable.

    However, when I check with SSH

    hdparm -d /dev/hdc3

    /dev/hdc3:
    using_dma = 0 (off)

    Well.. I noticed that cPanel click button doesn't run the right switch:

    They run:

    hdparm -c /dev/hdc5

    /dev/hdc5:
    IO_support = 1 (32-bit)

    So,.. could it be that cPanel need to correct the button to use the -d instead of the -c?
    Is this a bug that needs to go into Bugzilla or is it just me not understanding?


    Otherwise, how can I set it in shell? I'm just afraid to use the wrong switch.

    And,. since the 3 partitions that I use all reside on the same drive, do I just need
    to set it once with either one of them to make it happen? (at least this is my understanding).

    Disk hdc1 (/boot) No DMA! (Click to Enable)
    Disk hdc2 (/usr) No DMA! (Click to Enable)
    Disk hdc3 (/) No DMA! (Click to Enable)
    Disk hdc5 (/backup) No DMA! (Click to Enable)
    Disk lvmvol/home (/home)
    Disk lvmvol/var (/var)
    Disk sda1 (/mnt/scsihd)

    As you can understand and see .. hdc has various partitions in it.

    Thanks,

    -Alon.
     
  2. haze

    haze Well-Known Member

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    Normally with a newer OS you'll have DMA set up automatically. If you install your own kernel you'll have to do it yourself. You've taken the choice to install your own kernel you'll have to chase up the pieces now that thats been said and done. The cpanel DMA is really mostly for older OS's that don't have automatic detection.

    If you don't know which switches to use, DO NOT USE ANY, as it could render your system useless. You need to know first of all what make and brand of harddrive your using and what other hardware you have which connects your harddrive to your motherboard, and motherboard hardware knowledge doesn't hurt either. Then consult with the documentation for each and then research, research, research!!
     
  3. SupermanInNY

    SupermanInNY Well-Known Member

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    Research is what I'm doing! :)

    My board is an ASUS P4C800-E Deluxe and the HD is SATA, which supports the DMA (to my knowlege all SATA support DMA).
    So hardware wise, I'm set!
    You are correct about the kernel chases,. but I think the problem is more basic, the "Enable" switch that cPanel uses is the wrong switch in my opinion.
    They are setting the IO to 32 bit which is a good thing for itself, and that is set OK.
    The setting of the DMA on the other hand is using a different switch hdparm -d and cPanel appears to be running hdparm -c (notice the -c vs. -d).
    So,. although it reads "Enable DMA" , it is using the "Enable IO_32" instead. I think this is a simply wrong switch that is being used in cPanel... or a missing switch if you can run both parameters in the same command.

    The problem for me is that I'm not sure what is the SSH syntax to SET.
    I'm just using the GET command

    hdparm -d /dev/hdc3


    Which yields the following output:
    /dev/hdc3:
    using_dma = 0 (off)

    which display the info. Anyone knows the syntax to SET it to Enable (On or 1)?
    Do I need to reboot after it is being set?

    Just my $0.02.

    -Alon.
     
  4. haze

    haze Well-Known Member

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    From what i can see in the shell script thats used, both switches are there:

    /sbin/hdparm -q -u1 -c1 -q -A1 -q -m16 -q -d1 $dsk

    For the proper index, its probably best to view the manual pages for hdparm on your system. A reboot is not required, and also note that upon reboot the changes will be reset ( I think cpanel puts a file referencing the above in your rc.local or startup script )
     
  5. SupermanInNY

    SupermanInNY Well-Known Member

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    Well.. the issue while hasn't been resolved, has been identified as a Kernel Compile issue.

    We reverted back to the old kernel to identify if this was working and enabled in the previous kernel and found out that it was working fine.

    I've read the very same issue (even the same hardware as ours) in:

    http://www.linuxquestions.org/questions/showthread.php?s=&threadid=272670&goto=nextoldest

    While we are not using the RAID as in the article and we were using a higher kernel version, the issue is the same and by using lilo to go back to the old kernel, we identified that this feature was enabled and working fine and the kernel upgrade was the problem.

    Thanks for everyone's help on this.

    -Alon.
     
  6. networxhosting

    networxhosting Well-Known Member
    PartnerNOC

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    did you ever get this resolved with the stock kernels?

    Im having the exact same problems with a stock RHEL kernel with SATA drives, DMA will not enable

    Any ideas? anyone?
     
  7. SupermanInNY

    SupermanInNY Well-Known Member

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    Nope,.. haven't had any luck with that still.
    We looked at the configuration files in previous kernel's where the DMA is enabled, and there is no diff between them and the new configs.
    So there isn't really much that I can do at this time.

    Perhaps on the next kernel release it will be resolved.

    good luck.

    -Alon.
     
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