On Fri, Jan 17, 2014 at 06:24:26PM +0000, Duncan wrote: > Martin Walter posted on Fri, 17 Jan 2014 15:18:41 +0100 as excerpted: > > > Our problem is a zfs with 20,000 quota-enabled homedirectories and 100 > > snapshots. > > We would really like to do the same with btrfs, but we don't know how to > > replace the zfs quotas with btrfs subvolume quotas. It seems unfeasible > > to handle 2,000,000 subvolumes. > > e.g. we would have to create every hour 20,000 snapshots and delete the > > same amount. > > > > Is there any chance to get real user quotas with btrfs? > > At present I'd suggest staying away from quotas on btrfs in any case, as > there have been some serious bugs (quotas going negative with snapshot > deletion, etc) in the way they're tracked. I don't use quotas here so > haven't closely followed status and perhaps the bugs are fixed, but never- > the-less, it's something I'd recommend staying away from for the time > being. Certainly for usage at that scale. I'd suggest reexamining that > decision perhaps a year from now, but it's simply not ready for that, now. > > So I'd say stick with zfs for quota usage at that scale, for now. > > On a more general note, btrfs is just beginning to stabilize in > general... the kernel config warnings were just toned down for 3.13, > etc. However, as mkfs.btrfs warns when you create a btrfs filesystem, > it's still not entirely stable. This year should bring a lot of > stabilization as development focus gradually switches from features to > stabilization, but again, for production deployment at that scale, I'd > suggest waiting a year and reexamining the question. > > Of course you can still do pilot deployments now, but even more than with > fully stable filesystems, be sure you have current and tested backups, > because it's still possible you'll need to use them. Also, using the > current latest stable kernel (so 3.12.x currently, soon to be 3.13) if > not the development kernel is still recommended, as critical fixes still > go into every new kernel, and while they're marking more of them for > stable now, not all of them reach stable. Again, the warning was only > toned down with 3.13, so from there I'd hope they backport stable fixes, > but I wouldn't count on it before that. And btrfs-tools, while less > critical, is kernel-version synced from 3.12 as well, so you want a btrfs- > tools release at least reasonably comparable to your current kernel (v3.12 > current and minimum). > > (This as just a user and list regular, not a dev, myself.) I am actually very happy with btrfs. I use it everywhere, where I need no userquotas. Unfortunately subvolume quotas are not a real substitute for userquotas. Hopefully the developers will implement it someday. In any case, many thanks, Martin -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
