[mythtv-users] RAID 5 of different sized disks for mythtv storage?

David Rees drees76 at gmail.com
Mon Sep 11 21:37:48 UTC 2006


On 9/11/06, Paul V. Gratz <pgratz at gratz1.com> wrote:
>   I'm fairly early in the contemplation stage of setting up RAID for
> my backend storage needs.  Currently I've got LVM setup across three
> drives: part of a 250GB drive, all of a 200GB drive and all of a 300GB
> drive.  Those drives are broken up into 50GB partitions to make it
> easier to shift things around w/ LVM when the time comes.  I just
> bought a new 300GB drive.

I would really recommend that if you're going to use RAID 5 and are
concerned about performance, use 200gb partitions on 4 disks which
will leave you with 50gb extra on one disk and 100gb on 2. That will
give you 600gb redundant disk space.

Then you can raid 1 the other 100gb on the 2 300gb partitions, but
you'll be stuck with the 50gb extra, but that will add 100gb of
redundant disk space.

Or, also using the 50gb partition setup, create a bunch of raid5
arrays and then append them together (using software raid or LVM, your
choice), making sure that each raid5 array is built using a partition
from separate disks. Using this method, you can create 4 4-partition
raid5 arrays across all 4 disks (150gb ea/600gb total), 1 3-partition
raid5 (100gb) and 1 2-partition raid1 (50gb) for a total of 750gb.

Keep in mind that while the hybrid setups will work, but performance
won't be optimal on them, but that will get you the most usable disk
space.

Make sure you run regular SMART and raid consistency checks as if you
do happen to encounter a multi-disk failure, you will likely lose
everything so it's very important to catch any failing disks as soon
as possible.

-Dave


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