On 2012-04-05 15:17, Toby Corkindale 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.
>
> Consider buying some more 2TB disks (at $125 a pop they're not dear),
> and then building a new array.
>
> This time, build it with ZFS (or maaaaaybe btrfs if you dare), as with
> those you can add more disks (of variable size) later and rebalance files.

Also note that mdadm(1) states:

Grow    Grow  (or shrink) an array, or otherwise reshape it in some way.
       Currently supported growth options including changing the active
       size of component devices and changing the number of active
       devices in RAID levels 1/4/5/6, changing the RAID level between
       1, 5, and 6, changing the chunk size and layout for RAID5 and
       RAID5, as well as adding or removing a write-intent bitmap.

I've never tried the above, so don't know how reliable it is, but you
may be game enough to give it a go.