Re: Regular rebalancing should be unnecessary? (Was: Re: BTRFS free space handling still needs more work: Hangs again)

[Peter Waller <peter@scraperwiki.com>]

Apologies to those receiving this twice.

On 27 December 2014 at 09:30, Hugo Mills <hugo@carfax.org.uk> wrote:
>
> Now, since you're seeing lockups when the space on your disks is
>
> all allocated I'd say that's a bug. However, you're the *only* person
>
> who's reported this as a regular occurrence. Does this happen with all
> filesystems you have, or just this one?


I have experienced machine lockups on four separate cloud machines,
and reported it in a few venues. I think I even reported it on this
list in the past but I can't find that right now. Here's a bug report
to Ubuntu-Kernel:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1349711

Regularly rebalancing the machines and ensuring they have >10% free
disk (filesystem) and I don't experience this. Yet I read in this
thread I read that regular rebalancing shouldn't be necessary?

FWIW, trying to sell BTRFS to my colleagues and they view it as a
stupid filesystem "like the bad old windows days when you had to
regularly defragment". They then go on to say they have never
experienced machine lockups on EXT* (over a fairly significant length
of time).

So what can I tell them? Are we just hitting a bug which is likely to
get fixed, or must we regularly rebalance?

.. or is regularly rebalancing incorrect and actually regular machine
lockups are the expected behaviour? :-)