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

Robin Hill myth at robinhill.me.uk
Mon Sep 11 21:09:05 UTC 2006

On Mon Sep 11, 2006 at 03:53:02PM -0500, Paul V. Gratz wrote:

> Hey all,
>   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.  
>   Setting aside the issue of each drive needing to be on its own IDE
> bus (right now they share but I'm planning on picking up a new
> controller card to get to one drive per bus).  Is there a way to use
> RAID5 on 50GB partitions spread across several disks or is that asking
> for trouble.  I think I remember someone mentioning having that kind
> of setup.  Alternatively it sounds like I either need to get one more
> 300GB drive or settle on 250GBs for the RAID setup wasting the last
> 50GB of the two 300GB drives to make this work.  Is this correct?
I don't see why it wouldn't be possible.  The problem is that you'll
have all of the costs of RAID-5 (checksum calculation, etc) and none of
the benefits (since losing a disk will lose you more than one chunk,
hence the whole array will be trashed).  As you say, you're better
keeping one chunk per disk.  You don't have to waste the two 50GB chunks
of course - these could go into another array, perhaps a mirrored pair
for anything which needs fast access.

    ( ' }     |       Robin Hill        <myth at robinhill.me.uk> |
   / / )      | Little Jim says ....                            |
  // !!       |      "He fallen in de water !!"                 |
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