That would probably have helped. The XFS deadlocks would only occur when there was relatively little free memory. Kernel 3.18 is supposed to have a fix for that, but I haven't tried it yet.
Looking at my actual usage, I don't even need 64k inodes. 64k inodes should make things a bit faster when you have a large number of files in a directory. Ceph will automatically split directories with too many files into multiple sub-directories, so it's kinda pointless. I may try the experiment again, but probably not. It took several weeks to reformat all of the OSDS. Even on a single node, it takes 4-5 days to drain, format, and backfill. That was months ago, and I'm still dealing with the side effects. I'm not eager to try again. On Mon, Nov 17, 2014 at 2:04 PM, Andrey Korolyov <and...@xdel.ru> wrote: > On Tue, Nov 18, 2014 at 12:54 AM, Craig Lewis <cle...@centraldesktop.com> > wrote: > > I did have a problem in my secondary cluster that sounds similar to > yours. > > I was using XFS, and traced my problem back to 64 kB inodes (osd mkfs > > options xfs = -i size=64k). This showed up with a lot of "XFS: possible > > memory allocation deadlock in kmem_alloc" in the kernel logs. I was > able to > > keep things limping along by flushing the cache frequently, but I > eventually > > re-formatted every OSD to get rid of the 64k inodes. > > > > After I finished the reformat, I had problems because of deep-scrubbing. > > While reformatting, I disabled deep-scrubbing. Once I re-enabled it, > Ceph > > wanted to deep-scrub the whole cluster, and sometimes 90% of my OSDs > would > > be doing a deep-scrub. I'm manually deep-scrubbing now, trying to spread > > out the schedule a bit. Once this finishes in a few day, I should be > able > > to re-enable deep-scrubbing and keep my HEALTH_OK. > > > > > > Would you mind to check suggestions by following mine hints or hints > from mentioned URLs from there > http://marc.info/?l=linux-mm&m=141607712831090&w=2 with 64k again? As > for me, I am not observing lock loop after setting min_free_kbytes for > a half of gigabyte per OSD. Even if your locks has a different nature, > it may be worthy to try anyway. >
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