[SATLUG] lvm2 and raid 0

Brad Knowles brad at shub-internet.org
Mon Jan 7 12:31:47 CST 2008

On 1/7/08, Todd W. Bucy wrote:

>  I am getting ready to build a new box in the next couple of days.
>  However I can only afford two 500 gig drives.  I would eventually like
>  to expand to four or six 500 gig drives.  If I set my first two up as
>  Raid 1 can I latter and another drive and change to Raid 5 without
>  having to back up, format, and re-setup my system.  Or would I be better
>  off setting up an LVM.  I want the speed benefits as well as the
>  redundancy benefits of Raid but I also want the ease of adding
>  additional drives latter when I can afford them.

Unfortunately, normal host-type OSes don't make it quite so easy to 
"just throw in another disk and everything magically works", as 
compared to devices like the Infrant ReadyNAS NV+ or the Drobo -- 
otherwise, there wouldn't be anything that these companies could sell.

In particular, so far as I know, transparently and easily moving from 
a mirrored configuration to a RAID-5 type configuration is not 
something that can be done outside of devices like Infrant or Drobo, 
at least not for any price you'd be likely to be able to afford. 
When you get the new disks, you could take down the old array, 
rebuild the array with the new disks, and then restore your data from 
backup -- or the other disk that you leave out of the new array.

If you were using a ZFS-like storage pool solution, that might be 
able to handle the automatic addition/migration of disk space, 
because that kind of technology is at the core of the Drobo, and I 
have to believe that the Infrant guys are probably doing the same.

But beyond that, I'm not sure I can offer you any useful advice.

Brad Knowles <brad at shub-internet.org>
LinkedIn Profile: <http://tinyurl.com/y8kpxu>

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