(original article)

Re: A better way to grow a RAID with larger drives

03 October 2010, 05:13 UTC

This is actually why I usually build my RAID5 and RAID-4/5/6 setups with an extra MB or so 'wasted' by wrapping each individual drive in a RAID-1, and building the RAID-4/5/6 out of those single-drive RAID-1's.

Then growing to 'larger' drives involves no drive ever being marked faulty: I just add the new drive to the appropriate RAID-1, wait for it to sync with a bitmap (which is LIGHTNING fast since it's a pure linear read/write, no math involved) then remove the old, smaller drive from the RAID-1 and bump the size of the RAID-1.

It's a tiny bit of overhead and wasted space to cart around, but I disable bitmapping on the RAID-1 except when/if I'm swapping drives around, and leave bitmapping enabled on the RAID-4/5/6 regardless.