[nmglug] raid 10 vs 5

[Gary Sandine]

Hi Andres,

On Wed, Sep 09, 2009 at 04:13:51PM +0000, Andres Paglayan wrote:
>    quick question,
> 
>    If you have 4 x 1 TB disks, and they will be used for general purpose, (ie
>    db and file storage)
> 
>    how would you arrange them?
> 
>    raid 5 with one hot-spare?
>    or raid 1+0 (raid 10) stripping and mirroring?
> 
>    Both will provide 2 TB of available space,
>    will the raid 10 be faster I/O?

I would probably make a RAID 6 array because I think that should
always survive a double disk failure.  RAID 5 with a hot spare could
fail if a second disk fails while the hot spare is being included
(the rebuild can take a while for a 2 TB array), and RAID 10 could
fail if one of the mirrors loses its second disk before a RAID 1
component finishes mirroring onto a new disk.

I have only done RAID 6 with hardware RAID cards though (by Areca
and 3ware).  I think the Linux kernel software RAID driver supports
RAID 6 now.

Regards,
Gary