[linux-lvm] Re: raid 1 on a single disk

Piete Brooks Piete.Brooks at cl.cam.ac.uk
Sat Nov 13 11:03:00 UTC 2004

> yes i know its silly ... im doing what im told to do :p


Part of your job is to try to work out what they *meant* to tell you.

Explain what they are asking you to do (I've not yet grasped it), explain the 
problems with it (e.g. if the disk fails, all is lost), and offer suggestions 
as to what they might have wanted.

> ok so, i also do know, its performance is going to suck !


And what's the point?
It will protect against a single bad block, but not a disc failure.

> but i was under the impression that RAID 1 works on more that one disks only.

RAID doesn't know about discs (much -- it does try not to RESYNC multiple 
partitions on a single disc at once, as it causes head thrashing) -- it just 
deals in partitions. It doesn't care where they are.

But regardless of that, RAID1 is quite happy to run using a single partition

	mdadm -C -l1 -n2 /dev/md1 /dev/hda1 missing

> so you mean to say that, the linux RAID / md tools support raid 1 on
> multiple partitiions of the same disk ?

It doesn't care!

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