[dm-devel] Does dm-thin support GC (garbage collection) ?

[Joe Thornber]

On Tue, May 08, 2012 at 03:21:31PM +0800, Busby wrote:
>    I have tested that the blocks were reused in the other thin-lun of
> this pool  when deleted a thin-lun .
>    How can the blocks allocated for the thin-lun be dynamically
> reclaimed? (use some method like 'discard' to tell the pool which
> block should be reclaimed and whether the pool can reclaim it ?).
>    When I mounted a filesystem on a thin-lun, create 4G bytes file
> firstly, the pool have decreased  4G space, then I deleted the file,
> the pool did not increase the size as I thought, after this, create a
> 5G file, then the pool would decrease 1G size. So I think if the

Have you enabled discard support in both the thin-pool _and_ the
filesystem?  Have you confirmed that the filesystem issues the discard
in your test scenario?  (eg, via blktrace).

- Joe