Re: Again, no space left on device while rebalancing and recipe doesnt work

From: "Dāvis Mosāns" <davispuh@gmail.com>
To: Duncan <1i5t5.duncan@cox.net>
Cc: Btrfs BTRFS <linux-btrfs@vger.kernel.org>
Subject: Re: Again, no space left on device while rebalancing and recipe doesnt work
Date: Thu, 3 Mar 2016 17:39:12 +0200	[thread overview]
Message-ID: <CAOE4rSw_+PQEjAiHJkk03ec=J3ti9t9VCOD-zJSi=rP4dPnsjQ@mail.gmail.com> (raw)
In-Reply-To: <pan$1a785$dbfe4789$bdc8f4d5$778788dd@cox.net>

2016-03-03 6:57 GMT+02:00 Duncan <1i5t5.duncan@cox.net>:
>
> You're issue isn't the same, because all your space was allocated,
> leaving only 1 MiB unallocated, which isn't normally enough to allocate a
> new chunk to rewrite the data or metadata from the old chunks into.
>
> That's a known issue, with known workarounds as dealt with in the FAQ.
>

Ah, thanks, well it was surprising for me that balance failed with out of
space when both data and metadata had not all been used and I thought
it could just use space from those...

especially as from FAQ:
> If there is a lot of allocated but unused data or metadata chunks,
> a balance may reclaim some of that allocated space. This is the
> main reason for running a balance on a single-device filesystem.

so I think regular balance should be smart enough that it could
solve this on own and wouldn't need to specify any options.