On Sun, Dec 04, 2016 at 03:24:50PM -0800, Cyril Peponnet wrote: > > On Dec 4, 2016, at 2:46 PM, Dave Chinner <david@xxxxxxxxxxxxx> > > Which used LVM snapshots to take snapshots of the entire brick. > > I don't see any LVM in your config, so I'm not sure what > > snapshot implementation you are using here. What are you using > > to take the snapshots of your VM image files? Are you actually > > using the qemu qcow2 snapshot functionality rather than anything > > native to gluster? > > > > Yes sorry it was not clear enough, qemu-img snapshots no native > snapshots. Ok, so that's a fragmentation problem in it's own right. both internal qcow2 fragmentation and file fragmentation. > > Also, can you attach the 'xfs_bmap -vp' output of some of these > > image files and their snapshots? > > A snapshot: > https://gist.github.com/CyrilPeponnet/8108c74b9e8fd1d9edbf239b2872378d > (let me know if you need more basically there is around 600 live > snapshots sitting here). 1200 extents, mostly small, almost entirely adjacent. Typical qcow2 file fragmentation pattern. That's not going to cause your memory allocation problems - can you find one that has hundreds of thousands of extents? > > > > 56GB of cached file data. If you're getting high order > > allocation failures (which I suspect is the problem) then this > > is a memory fragmentation problem more than anything. > > > >> ---------------------------------------------------------------- > >> DG/VD TYPE State Access Consist Cache Cac sCC Size Name > >> ---------------------------------------------------------------- > >> 0/0 RAID0 Optl RW Yes RAWBC - ON 7.275 TB scratch > >> ---------------------------------------------------------------- > >> > >> Cac=CacheCade|Rec=Recovery|OfLn=OffLine|Pdgd=Partially > >> Degraded|dgrd=Degraded Optl=Optimal|RO=Read Only|RW=Read > >> Write|HD=Hidden|B=Blocked|Consist=Consistent| R=Read Ahead > >> Always|NR=No Read Ahead|WB=WriteBack| AWB=Always > >> WriteBack|WT=WriteThrough|C=Cached IO|D=Direct IO|sCC=Scheduled > > > > IIRC, AWB means that if the cache goes into degraded/offline > > mode, you’re vulnerable to corruption/loss on power > > failure… > > Yes we have BBU + redundant PSU to address that. BBU fails, data center loses power, corruption/data loss still occurs. Not my problem, though. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
