As I understand it, reshape for RAID6 is coming now.  It is in the 2.6.21 kernel still at rc4 as of today though.  I am looking forward to it, and plan to give it a test run when it released.

I have used lv with my past raid sets and it is very nice, adds some flexibility.  

I have also done a RAID5 reshape that was in an lv.  Unfortunately, at the time I had an older LVM version that did not support pvresize.  So I was stuck with a larger RAID set and my lv would not take advantage of it.

I think I needed LVM version 2.02.06 to solve that and get the pvresize feature. If you are running a relatively new disto that won't be an issue any more.  I think I had FC3 or 4.

-----Original Message-----
From: Gordon Henderson [mailto:gordon@drogon.net] 
Sent: Friday, March 23, 2007 11:35 AM
To: Mattias Wadenstein
Cc: linux-raid@vger.kernel.org
Subject: Re: Grow a RAID-6 ?

On Fri, 23 Mar 2007, Mattias Wadenstein wrote:

On Fri, 23 Mar 2007, Gordon Henderson wrote:

quoted

Are there any plans in the near future to enable growing RAID-6 arrays by 
adding more disks into them?

I have a 15x500GB - drive unit and I need to add another 15 drives into 
it... Hindsight is telling me that maybe I should have put LVM on top of 
the RAID-6, however, the usable 6TB it yields should have been enough for 
anyone...

Well, if you are doubling the space, you could take this opportunity to put 
lvm on the new disks, move all the data, then put in the old disks as a pv, 
extending the lvm space.

Now why didn't I think of that. *thud*

I really wouldn't recommend having a 30-disk raid6, imagine the rebuild time 
after a failed disk..

There is that - it would give me 2 disks (ie. 1TB) more space though...

This isn't a performance limited server though, it's an off-site backup 
box, so it just has to be reasonably reliable.

Thanks!

Gordon
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