Re: defrag xfs

[Andi Kleen <ak@xxxxxx>]

> Now, what would be really neat is for a layer underneath the filesystem
> to dynamically detect failing storage (smart?), take some storage from
> a free pool of drives, and remap the filesystem blocks out to the new
> space while it is live.

Aka drivers/md/dm-bbr.c. It's not in mainline (yet?), but somewhere in the 
DM patchkits. However it obviously only works for write errors, to handle
read errors you need a RAID level >0.

-Andi