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

Jafa hdtv at silicondust.com
Mon Sep 11 21:23:28 UTC 2006

>   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've read the two wiki pages on the subject but they don't really
> answer my question (although it looks like they have great info on how
> to set it up once I figure out the partitioning stuff).
Hi Paul,

A mixture of RAID and LVM would work.

Easiest example:

1st RAID (600GB storage):
200GB of the 250GB drive.
200GB of the 250GB drive.
200GB of the 300GB drive.
200GB of the new 300GB drive.

2nd RAID (100GB storage):
100GB of the 300GB drive.
100GB of the new 300GB drive.

LVM: 1st RAID + 2nd RAID = 700GB.

If you like working with 50GB partitions then that will work ok as well 
- just make sure that you don't allocate two partitions on the same disk 
to the same RAID. You will end up with 6 RAID systems (4 systems with 
50GB x 4 disks and 2 systems with 50GB x 2 disks)... then LVM them all 

I am tempted to do something similar.


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