RE: Software RAID1

From: Gayn Winters (gayn.winters_at_bristolsystems.com)
Date: 09/15/05

  • Next message: Jerry McAllister: "Re: Software RAID1"
    To: "'Jason King'" <jking@informs.com>, <freebsd-questions@freebsd.org>
    Date: Thu, 15 Sep 2005 09:12:10 -0700
    
    

    > -----Original Message-----
    > From: owner-freebsd-questions@freebsd.org
    > [mailto:owner-freebsd-questions@freebsd.org] On Behalf Of Jason King
    > Sent: Thursday, September 15, 2005 5:16 AM
    > To: freebsd-questions@freebsd.org
    > Subject: Software RAID1
    >
    >
    > I am having trouble with THESE instructions:
    > http://people.freebsd.org/~rse/mirror/
    >
    > I'm trying to create a RAID1 system with FreeBSD and the instructions
    > are not working. I'm getting this error:
    >
    > mail# gmirror insert gm0 /dev/da0
    > Cannot access provider da0.
    >
    > The command is trying to add the first disk /dev/da0 to the
    > mirror gm0.
    > Has anyone else had success at creating a RAID1 mirror on FreeBSD. If
    > so, please let me know how you did it because these
    > instructions are not
    > working at all.
    >
    > Jason
    > _______________________________________________

    Those instructions work fine, but you have to be very careful following
    them. (See below)

    An alternate way to use gmirror for software mirroring as is described
    in

    http://dannyman.toldme.com/2005/01/24/freebsd-howto-gmirror-system/

    These work fine as well.

    Ralf's instructions, which you quote above, have the advantage of not
    needing to go into Fixit mode using the 5.4 boot CD (hence it can be
    executed remotely); however, it takes more typing and more reboots.

    If you use the latter, note that Ralf uses ATA drives ad0 and ad1, while
    it looks like you may have da0 and da1. You need to make the
    appropriate transliteration ad --> da very carefully, especially in the
    line for the boot loader where ad(1,a) --> da(1,a).

    This latter paper also outlines how to mirror at the slice, rather than
    the disk, level.

    One final hint: if you are playing around with gmirror on the same
    disks, you can get into a situation where one attempt has left gmirror
    information on the last sector of your disks. This will confuse
    gmirror, and you will have to load and use gmirror to clear it out. (or
    zero the entire disk with dd if=/dev/zero.) Read the man pages on
    gmirror in any case!!!

    Best of luck,

    -gayn

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