RAID 1 - Questions

This is a discussion on RAID 1 - Questions ; Hi, I am running RH 9.0 with two WD 40GB HDs in a RAID 1 (Mirror). This is just a test system. So while the system was booting up I pulled the power on hdb just to see what would ...

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Thread: RAID 1

  1. RAID 1

    Hi,

    I am running RH 9.0 with two WD 40GB HDs in a RAID 1 (Mirror). This is just
    a test system. So while the system was booting up I pulled the power on hdb
    just to see what would happen. The system looked for hdb for a little while
    then booted up fine.

    I then shutdown the system and unplugged hda and made hdb the master (only
    HD in the system). When I booted up the system I got an error saying
    "Missing Operating System...". I then plugged both HDs back in as
    master/slave (just like they were before I pulled the power on hdb) and the
    system found BOTH drives and booted just fine.

    I checked (using DOS fdisk) to make sure hdb was set to "Active" and it was.
    Anyone have any ideas how to get hdb to boot if hda fails?

    Let's say I replace hdb with a new HD. How would I get hda to regenerate
    it's data to the new drive?

    Thanks for any help.

    Lamar



  2. Re: RAID 1

    ["Followup-To:" header set to comp.os.linux.networking.]
    On Fri, 26 Dec 2003 17:48:04 GMT, Lamar Thomas wrote:
    > Hi,
    >
    > I am running RH 9.0 with two WD 40GB HDs in a RAID 1 (Mirror). This is just
    > a test system. So while the system was booting up I pulled the power on hdb
    > just to see what would happen. The system looked for hdb for a little while
    > then booted up fine.


    I hope you don't mean while it was on. IDE hot-swap is sketchy at best.

    > I then shutdown the system and unplugged hda and made hdb the master (only
    > HD in the system). When I booted up the system I got an error saying
    > "Missing Operating System...". I then plugged both HDs back in as
    > master/slave (just like they were before I pulled the power on hdb) and the
    > system found BOTH drives and booted just fine.


    Is this with software RAID? If so, you probably aren't (and can't, AFAIK)
    mirror the boot sector, so you have to make it manually on /dev/hdb. You
    probably should consider moving the primary slave to secondary master for
    performance reasons, too.

    > I checked (using DOS fdisk) to make sure hdb was set to "Active" and it was.
    > Anyone have any ideas how to get hdb to boot if hda fails?
    >
    > Let's say I replace hdb with a new HD. How would I get hda to regenerate
    > it's data to the new drive?


    Use raidhotadd, like this:

    raidhotadd /dev/md0 /dev/hdb

    --
    -- Skylar Thompson (skylar@cs.earlham.edu)
    -- http://cs.earlham.edu/~skylar/

  3. Re: RAID 1

    Lamar Thomas wrote:

    > Hi,
    >
    > I am running RH 9.0 with two WD 40GB HDs in a RAID 1 (Mirror). This is
    > just
    > a test system. So while the system was booting up I pulled the power on
    > hdb
    > just to see what would happen. The system looked for hdb for a little
    > while then booted up fine.
    >
    > I then shutdown the system and unplugged hda and made hdb the master (only
    > HD in the system). When I booted up the system I got an error saying
    > "Missing Operating System...". I then plugged both HDs back in as


    Sounds like only the bootsector on the original hda has anything in it.

    Is this linux software raid or hardware raid ?

    > master/slave (just like they were before I pulled the power on hdb) and
    > the system found BOTH drives and booted just fine.
    >
    > I checked (using DOS fdisk) to make sure hdb was set to "Active" and it
    > was. Anyone have any ideas how to get hdb to boot if hda fails?
    >
    > Let's say I replace hdb with a new HD. How would I get hda to regenerate
    > it's data to the new drive?
    >
    > Thanks for any help.
    >
    > Lamar



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