Re: RAID10 Balancing Request for Comments and Advices

Chris Murphy
2015-06-17T00:14:06Z

On Tue, Jun 16, 2015 at 5:58 PM, Duncan <1i5t5.duncan@cox.net> wrote:

> On a current kernel unlike older ones, btrfs actually automates entirely
> empty chunk reclaim, so this problem doesn't occur anything close to near
> as often as it used to. However, it's still possible to have mostly but
> not entirely empty chunks that btrfs won't automatically reclaim. A
> balance can be used to rewrite and combine these mostly empty chunks,
> reclaiming the space saved. This is what Hugo was recommending.

Yes, as little as a -dusage=5 (data chunks that are 5% or less full)
can clear the problem and is very fast, seconds. Possibly a bit
longer, many seconds o single digit minutes is -dusage=15. I haven't
done a full balance in forever.

--
Chris Murphy