[Techtalk] formatting half a mirrored raid...

Conor Daly conor.daly at oceanfree.net
Fri Jun 13 10:51:14 EST 2003

On Thu, Jun 12, 2003 at 09:10:27PM -0400 or so it is rumoured hereabouts, 
Walt thought:
> (md1 is the new raid, md0 is the old)
>    Personalities : [raid0] [raid1]
>    md1 : active raid0 sdd1[2] sdc1[1] sdb1[0]
>          215479488 blocks 32k chunks
>    md0 : active raid1 hda1[0]
>          117218176 blocks [2/1] [U_]

You should consider your raid types you are using here.  Your md1 is raid0
which gives you no redundancy.  Instead it will give you 3x73Gb of space.
If that is your intention, fine but be aware of that (given that you were
using raid1 to mirror on md0 I wonder if raid0 was your intention for
md1).  If you _do_ wish to use raid0, consider the options related to
striping or not.  If you use striping, the loss of one disk loses your
_entire_ data on the full raid set.  Use striping if performance is an
issue.  If, OTOH, you use "linear" for this raid set, the disks will
simply be concatenated and loss of a disk will mean loss of _only_ the
data stored on that disk.

Now, if you want _redundancy_, you should consider either raid3 or raid5
where you will be able to rebuild your data should you lose a disk.
However, you'll end up with only 2x73Gb of space.

Conor Daly <conor.daly at oceanfree.net>

Domestic Sysadmin :-)
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