How to check software RAID status?

Discussion in 'General' started by westcomlimited, Feb 9, 2011.

  1. westcomlimited

    Joined:
    Dec 3, 2010
    Messages:
    14
    Likes Received:
    0
    I have a relatively new install of Elastix that I cannot remember if I setup software RAID on or not when I installed it.

    If there some way I can tell if it is Mirrored?

    I tried running cat /proc/mdstat but all it returned was:

    Personalities :
    unused devices: <none>

    This looks to me like it is not RAID or it is not detecting it correctly.
     
  2. dicko

    Joined:
    Oct 24, 2008
    Messages:
    4,099
    Likes Received:
    0
    Your disk partitions will be exposed with:-

    cat /proc/partitions

    Real Raids will usually expose themselves here, the won't be /dev/hda? or /dev/sda?
    , mostsocalled motherboard raids are software based, and to be honest , are far worst preforming and more error prone than a linux software raid.
     
  3. dicko

    Joined:
    Oct 24, 2008
    Messages:
    4,099
    Likes Received:
    0
    Your disk partitions will be exposed with:-

    cat /proc/partitions

    Real Raids will usually expose themselves here, the won't be /dev/hda? or /dev/sda?
    , mostsocalled motherboard raids are software based, and to be honest , are far worse preforming, un-tunable and more error prone than a linux software raid.
     
  4. westcomlimited

    Joined:
    Dec 3, 2010
    Messages:
    14
    Likes Received:
    0
    Here is the output of that command
    major minor #blocks name

    8 0 78156288 sda
    8 1 104391 sda1
    8 2 78051802 sda2
    8 16 78156288 sdb
    8 17 78156193 sdb1
    253 0 152043520 dm-0
    253 1 4128768 dm-1


    Looks like it is Mirrored?

    In case it wasn't clear I am asking about a Elastix installed Software Mirror, not any other type of RAID.
     
  5. dicko

    Joined:
    Oct 24, 2008
    Messages:
    4,099
    Likes Received:
    0
    Not at the Centos OS level vm extends your root across two drives and you only have a boot partion on sda , good luck when a drive breaks :)

    dicko
     
  6. fmvillares

    Joined:
    Sep 8, 2007
    Messages:
    1,785
    Likes Received:
    0
    agree with dicko ...buy a real raid 1 system...you re not protected right now
    and 1 item to share...if a file gets corrupted in a raid or the particion breaks the raid will be copying across the mirror that information also...so any raid 1 or 5 or 10 only protects you of hardware failures...not errors up to the software world...
     
  7. westcomlimited

    Joined:
    Dec 3, 2010
    Messages:
    14
    Likes Received:
    0
    I am aware of how RAID works thanks so I am of course aware that it will not protect against software failure.

    Perhaps you misunderstood the term "software RAID"
    What I thought was common knowledge is that software RAID is setup by an OS and not a battery backed up hardware controller.

    I admit I am not very linux savy, but all I want is to setup a linux software RAID mirror for elastix.

    It was my impression that Elastix could do this at installation, are you saying that this is not the case?
     
  8. dicko

    Joined:
    Oct 24, 2008
    Messages:
    4,099
    Likes Received:
    0
    Yes you can as you install Elastix by manually partitioning the two drives, I suggest something like for a raid 1 :-

    100 M for /boot use /dev/sda1 and /dev/sdb1 as /dev/md0
    1.5 * memory for swap use /dev/sda2 and /dev/sda2 as /dev/md1
    6G for / use /dev/sda3 /dev/sdb3 as /dev/md2
    the rest for /var use /dev/sda4 /dev/sdb4 as /dev/md3

    make each partition of type fd (raid partition), then build the md0-md3 from those partitions.

    Alternatively do a mondoarchive iso/usb/nfs image, and restore from that into a manually prepared partition system, (much like the above) you'll need to do a little RTFM'ing to get the handle of mondoarchive/mondorestore do the expert thing and issue an export TERM=vt100 so you don't go blind :)

    It is possible to migrate to raid "on the fly" there are a few recipes here and else where, but it's a little ballsy and you will need a third disk temporarily as the default partitioning uses volume manager and extends everything over both drives.

    When done, make sure grub is installed on both /dev/sda and /dev/sdb

    (I'm sure you also know not to confuse a real raid controller with a cheap motherboard raid controller, I say this as your posted bug says you have a raid 5 hardware controller, but your previous post seems to identify two raw scsi/sata disks )
     
  9. westcomlimited

    Joined:
    Dec 3, 2010
    Messages:
    14
    Likes Received:
    0
    OK thanks again Dicko

    My bug report is from a different machine to what I am wanting to RAID, as you said that machine has a hardware RAID 5.
     

Share This Page