removing / replacing in-use components in gvirstor

[Eric Anderson]

John Nielsen wrote:
> Ivan-
> 
> I was happy to see in the FreeBSD status report that gvirstor has been 
> committed to CVS and will be in RELENG_7. Obviously this is great 
> functionality with many potential uses. Thanks for your great work and 
> efforts to get it committed!
> 
> In thinking about how I personally would use it, I realized I would add 
> drives to a system until I ran out of slots or controller connections, and 
> then want to upgrade to larger drives. From the manpage (and the code) it 
> doesn't look like this is currently possible unless the drive you want to 
> replace happens to be unused. How feasible would it be to either extend 
> the "remove" verb to migrate in-use chunks to other (existing) providers or 
> create a "replace" verb to migrate in-use chunks to a new provider?

I wonder if making each drive a member of a single-device mirror, and 
then including all the mirrors into the gvirstor GEOM would do the 
trick.  That way, you can simply add a new drive to the mirrorset you 
want to replace, let the mirror sync, and then pop the old drive out.  I 
think the only remaining step is to re-mirror the mirror, or extend the 
mirror or partition..

Eric