Am Sun, 14 May 2017 13:15:09 -0700 schrieb Marc MERLIN <m...@merlins.org>:
> On Sun, May 14, 2017 at 09:13:35PM +0200, Hans van Kranenburg wrote: > > On 05/13/2017 10:54 PM, Marc MERLIN wrote: > > > Kernel 4.11, btrfs-progs v4.7.3 > > > > > > I run scrub and balance every night, been doing this for 1.5 > > > years on this filesystem. > > > > What are the exact commands you run every day? > > http://marc.merlins.org/perso/btrfs/post_2014-03-19_Btrfs-Tips_-Btrfs-Scrub-and-Btrfs-Filesystem-Repair.html > (at the bottom) > every night: > 1) scrub > 2) balance -musage=0 > 3) balance -musage=20 > 4) balance -dusage=0 > 5) balance -dusage=20 > > > > How did I get into such a misbalanced state when I balance every > > > night? > > > > I don't know, since I don't know what you do exactly. :) > > Now you do :) > > > > My filesystem is not full, I can write just fine, but I sure > > > cannot rebalance now. > > > > Yes, because you have quite some allocated but unused space. If > > btrfs cannot just allocate more chunks, it starts trying a bit > > harder to reuse all the empty spots in the already existing > > chunks. > > Ok. shouldn't balance fix problems just like this? > I have 60GB-ish free, or in this case that's also >25%, that's a lot > > Speaking of unallocated, I have more now: > Device unallocated: 993.00MiB > > This kind of just magically fixed itself during snapshot rotation and > deletion I think. > Sure enough, balance works again, but this feels pretty fragile. > Looking again: > Device size: 228.67GiB > Device allocated: 227.70GiB > Device unallocated: 993.00MiB > Free (estimated): 58.53GiB (min: 58.53GiB) > > You're saying that I need unallocated space for new chunks to be > created, which is required by balance. > Should btrfs not take care of keeping some space for me? > Shoudln't a nigthly balance, which I'm already doing, help even more > with this? > > > > Besides adding another device to add space, is there a way around > > > this and more generally not getting into that state anymore > > > considering that I already rebalance every night? > > > > Add monitoring and alerting on the amount of unallocated space. > > > > FWIW, this is what I use for that purpose: > > > > https://packages.debian.org/sid/munin-plugins-btrfs > > https://packages.debian.org/sid/monitoring-plugins-btrfs > > > > And, of course the btrfs-heatmap program keeps being a fun tool to > > create visual timelapses of your filesystem, so you can learn how > > your usage pattern is resulting in allocation of space by btrfs, > > and so that you can visually see what the effect of your btrfs > > balance attempts is: > > That's interesting, but ultimately, users shoudln't have to > micromanage their filesystem to that level, even btrfs. > > a) What is wrong in my nightly script that I should fix/improve? You may want to try https://www.spinics.net/lists/linux-btrfs/msg52076.html > b) How do I recover from my current state? That script may work it's way through. -- Regards, Kai Replies to list-only preferred. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
