Raid 1 software - Hardware

This is a discussion on Raid 1 software - Hardware ; Hi, need an answer .... we have a linux server (file and web server) running on only one hard disk. For backup reason, is it possible to make a raid 1 software only adding a second hard drive , without ...

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Thread: Raid 1 software

  1. Raid 1 software

    Hi,
    need an answer .... we have a linux server (file and web server) running on
    only one hard disk. For backup reason, is it possible to make a raid 1
    software only adding a second hard drive , without re installing the whole
    machine ?

    thanks a lot,

    Tanja



  2. Re: Raid 1 software

    "Tanja" writes:
    >Hi,
    >need an answer .... we have a linux server (file and web server) running on
    >only one hard disk. For backup reason, is it possible to make a raid 1
    >software only adding a second hard drive , without re installing the whole
    >machine ?


    Yes, but it's quite a bit of work:

    0) Make sure your kernel supports the RAID1 (CONFIG_MD=y CONFIG_MD_RAID1=y).

    1) Partition the new drive

    2) Create RAID1 devices, but at first with only the partitions from
    the new drive (i.e., no redundancy at first).

    3) Make filesystems on the RAID1 devices.

    4) Copy the filesystems to the RAID1 devices (the originals should all
    be read-only during this) and adjust the fstab to point to the RAID1
    devices.

    5) Adjust the boot software to boot from the new disk with root on a
    RAID1 device.

    6) Reboot.

    7) Now repartition (if necessary) the old drive and add the partitions
    to the RAID1 devices.

    8) Adjust your boot software so that it can boot from either disk.

    - anton
    --
    M. Anton Ertl Some things have to be seen to be believed
    anton@mips.complang.tuwien.ac.at Most things have to be believed to be seen
    http://www.complang.tuwien.ac.at/anton/home.html

  3. Re: Raid 1 software

    Tanja wrote:

    > need an answer .... we have a linux server (file and web server) running on
    > only one hard disk. For backup reason, is it possible to make a raid 1
    > software . . .


    Just something to keep in mind about this. RAID should never be
    considered a substitute for a proper backup strategy. If the only
    copy of the data resides on the two spindles of a RAID-1 array, and
    something goes wrong that say erases everything or something causes
    the system to scrible all over the thing (something I've actually
    encountered)--all your data is gone.

    This isn't to say RAID is useless, it's more about dealing gracefully
    with fault tolerance (i.e., hardware failure) than about archives.


    --

    If you want to reply via email, change the obvious words to numbers and
    remove ".invalid".

  4. Re: Raid 1 software

    On Thu, 18 Jan 2007 09:34:22 +0100, Tanja wrote:


    >Hi,
    >need an answer .... we have a linux server (file and web server) running on
    >only one hard disk. For backup reason, is it possible to make a raid 1
    >software only adding a second hard drive , without re installing the whole
    >machine ?


    A think a bigger issue is the fact that you're unable to operate a web
    browser, find a search site like google, and figure out something clever
    to search for like "linux raid 1". Somebody lacking those skills shouldn't
    be messing around with physical storage issues.


  5. Re: Raid 1 software

    On Thu, 18 Jan 2007 12:58:25 -0600, Michael Faurot wrote:


    >Tanja wrote:


    >> need an answer .... we have a linux server (file and web server) running on
    >> only one hard disk. For backup reason, is it possible to make a raid 1
    >> software . . .


    >Just something to keep in mind about this. RAID should never be
    >considered a substitute for a proper backup strategy. If the only
    >copy of the data resides on the two spindles of a RAID-1 array, and
    >something goes wrong that say erases everything or something causes
    >the system to scrible all over the thing (something I've actually
    >encountered)--all your data is gone.


    Absolutely. Delete a file and it'll vanish from both drives.
    A software error will hapily corrupt both your drives and a bad power supply
    can smoke both drives. Backups must be kept offline when not in use and
    should be only mounted readonly when needed. THere should also be backups
    kept off site.

  6. Re: Raid 1 software

    AZ Nomad writes:
    >A think a bigger issue is the fact that you're unable to operate a web
    >browser, find a search site like google, and figure out something clever
    >to search for like "linux raid 1".


    For other topics this is certainly good advice, but unfortunately not
    for Linux RAID1. Much of the software has changed since most of the
    HOWTOs that one finds have been written. /etc/raidtab is no longer
    needed, and tools like mkraid etc. have been replaced with mdadm.

    Of course, the original poster might have an old system that still has
    the old tools, then the old HOWTOs will be right on target.

    - anton
    --
    M. Anton Ertl Some things have to be seen to be believed
    anton@mips.complang.tuwien.ac.at Most things have to be believed to be seen
    http://www.complang.tuwien.ac.at/anton/home.html

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