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Re: Root on RAID

>>>>> "Alvin" == Alvin Oga <aoga@Maggie.Linux-Consulting.com> writes:

    Alvin> hi ya george

    Alvin> for raid1....  typically /dev/hda is copied to /dev/hdb

    Alvin> 	- dont know why you'd wanna mirror a partition...  (
    Alvin> system will still be dead since the rest of the required (
    Alvin> partition is not available

Easy, you create a separate software-RAID1 partition for every
partition on you harddisk, so in affect you mirror one harddisk on to
the other harddisk.

It might be possible (?) to mirror /dev/hda to /dev/hdb, but then you
need to subdivide that space up into partitions.

lvm could be used to do this (AFAIK), but all my attempts to use lvm
up to now have failed.

Even then, I imagine it would be harder/impossible to do some things
which are possible with a separate RAID partition, eg:

recently my 20 Gig harddisk failed (or at least showed serious looking
"unrecoverable" DMA transfer errors), and I didn't trust the other one
either. I only had 2 * 8 gigs harddisk spare.

It is an easy matter to create partitions the same size (or bigger) as
the important partitions on the remaining drive, and mirror them. If I
mirrored the entire drive, this would not be possible, I would need
total space at least 20Gigs big.

Of course, one of my partitions was 10Gig, so this wasn't going to
work here, so I tried to install a large lvm partition on both hard
disks. However, my attempts failed, as I couldn't do the 2nd step
(create a virtual drive from the physical drive, it kept saying no
physical drives found).

As for now, I have replaced the dead harddisk, and everything is
working fine (for the moment).
Brian May <bam@debian.org>

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