Is that because the disk was removed from the array and/or lost its
superblock info?

I've had problems with arrays before during resync, and I was able to
stop them and resume them again, sometimes after disks jump out of the
array (but still retaining their superblock info).

On Thu, Dec 17, 2009 at 2:22 PM, Michael Evans [off-list ref] wrote:

He's using v0.9 superblocks; even if the replaced device was at 99%
complete it would still have to restart from 0% when re-added.

-- 
       Majed B.