Moving a PV onto raid

[Russell Coker]

On Thu, 5 Apr 2012, Toby Corkindale <toby.corkindale at strategicdata.com.au> 
wrote:
> On 05/04/12 13:46, Brett Pemberton wrote:
> > A home system has N number of 1.5TB drives, running in RAID5.
> > At one point, these drives stopped becoming available, so the last time
> > I extended the array, I used a 2TB drive.
> > Now that a 1.5TB drive has failed, I'm replacing it with another 2TB
> > drive, and wondering the best way to use the remainder 500GB
> > Is there a better plan?
> 
> If two disks have failed and aren't available commercially any more, I'd
> say it's likely the rest will go sooner rather than later because
> they're all getting too old.

I've got a bunch of servers with RAID-1 arrays as small as 20G.  There's one 
server that I'd really like to reinstall but it has been running on a pair of 
20G disks since 2006 without a break.

http://etbe.coker.com.au/2008/10/14/some-raid-issues/
http://etbe.coker.com.au/2012/02/06/reliability-raid/

That said, I wouldn't be using RAID-5 for large storage that's important.  
Even RAID-1 has issues.  It's best to use something like BTRFS or ZFS for 
reliability.

On Thu, 5 Apr 2012, Chris Samuel <chris at csamuel.org> wrote:
> I don't believe you can do this with btrfs, if you define a RAID1 array
> (for instance) with different size drives you will get ENOSPC when you
> fill the smaller one as it can no longer distribute to both.

Surely if you tell it to use RAID-1 and give it more than 2 disks then it can 
somehow work things out?

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