The Community Forums

Interact with an entire community of cPanel & WHM users!
  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Missing swap partition

Discussion in 'General Discussion' started by JayAtjeu, Oct 3, 2006.

  1. JayAtjeu

    JayAtjeu Member

    Joined:
    Apr 27, 2006
    Messages:
    6
    Likes Received:
    0
    Trophy Points:
    1
    One of our clients with a dedicated system noticed today after nearly a year with the server that it doesn't have a swap partition. Now I am pretty sure that we installed it with a partition so my intuition tells me that this is a recent developement because he should be seeing a lot more load problems if he had no swap partition before now I think. At any rate can anyone think of what might cause the swap partition to dissappear. I'm not talking just about it being unmounted either, as it doesn't even register the /dev/sda3 partition in fdisk -l

    Here's the listing out of top so you see what I mean:
    Mem: 2074892k total, 1747268k used, 327624k free, 60540k buffers
    Swap: 0k total, 0k used, 0k free, 1040040k cached

    here's fdisk -l:
    root [~]# fdisk -l

    Disk /dev/sda: 300.0 GB, 300090728448 bytes
    255 heads, 63 sectors/track, 36483 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sda1 * 1 13 104391 83 Linux
    /dev/sda2 14 36483 292945275 fd Linux raid autodetect

    Disk /dev/sdb: 300.0 GB, 300090728448 bytes
    255 heads, 63 sectors/track, 36483 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sdb1 * 1 36470 292945243+ fd Linux raid autodetect

    Disk /dev/md0: 299.9 GB, 299975835648 bytes
    2 heads, 4 sectors/track, 73236288 cylinders
    Units = cylinders of 8 * 512 = 4096 bytes

    Disk /dev/md0 doesn't contain a valid partition table


    So if you know a way to create a partition for swap after the fact or know of anyway to that it could have dissappeared I'd appreciate the assistance.

    I should also add that he said he upgraded the kernel recently to 2.6.9-42.0.2ELsmp, might that effect this?
     
  2. ujr

    ujr Well-Known Member

    Joined:
    Mar 19, 2004
    Messages:
    290
    Likes Received:
    0
    Trophy Points:
    16
    I dont know why I stumbled on this but here is the delayed answer (albeit 2 months later):

    mkswap -f /dev/hdaX
    swapon /dev/hdaX

    then add it to fstab:

    /dev/hdaX swap swap defaults 0 0

    hdaX would be your drive partition for the swap. You may want to note that you can place it on a second drive to ... ie hdbX. Sometimes placing the swap on the outer frindges of the drive will also inprove performance.

    If you don't have a partition made for it, you may need to repartition your drives.

    However, you can also do this, if you are in need of a file-based swap. This is a really good solution if you are also out of swap drive space:

    dd if=/dev/zero of=/var/fileswap bs=1024 count=65536

    this 65536 size is 64MB, alternatively for even larger, just multiply the MB x 1024 and use that.

    then, you will need to mount your new fileswap like so:

    mkswap -f /var/fileswap
    swapon /var/fileswap

    and to remove it in the future use swapoff command then rm the file.

    Hope this helps you or anyone else ;)
     
  3. isputra

    isputra Well-Known Member

    Joined:
    May 3, 2003
    Messages:
    576
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Mbelitar
    Is it save to do ujr howto on centos 4.5 ?
     
  4. isputra

    isputra Well-Known Member

    Joined:
    May 3, 2003
    Messages:
    576
    Likes Received:
    0
    Trophy Points:
    16
    Location:
    Mbelitar
    Ok, thanks ujr :D

    Your method works for me.
     
Loading...

Share This Page