Marc MERLIN posted on Sun, 20 Apr 2014 12:59:01 -0700 as excerpted: > I was looking at using qgroups for my backup server, which will be > filled with millions of files in subvolumes with snapshots. > > I read a warning that quota groups had performance issues, at least in > the past.
Yes. Additionally, there were serious bugs such that after subvolume deletes people would end up with negative quota usage! Luckily I didn't need that for my use-case, but the recommendation for a couple kernels was definitely to avoid it for the time being, unless you were simply playing with it. There were/are other filesystems with more mature quota solutions that actually work, if you're going to depend on it actually working. > Is it still true? Very good question. Certainly both the qgroups bug reports and the patches have slowed down for 3.13/3.14 so it's gotta be better than it was, and while I don't use that feature and thus haven't been tracking it directly, I believe current status should be about where generic btrfs is at this point, that is, reasonably stable, but keep your backups tested and ready, just in case. > If there is a performance issue, is it as simple as just turning off > quota support and then things go back to normal? IIRC yes, even back when the bugs were coming in right and left, that was basically the case -- WITH THE CAVEAT that back then anyway, a reboot was sometimes needed as the counts just weren't being updated correctly and people were getting some very weird results on deletion/disabling until reboot, sometimes. Meanwhile, looking forward to your testing/reports/wiki-updates! If you can do for qgroups what you've been doing for raid5/6 mode I'm sure a lot of folks (including me, I might not use it presently, but the better I understand it, the more effectively I can help others with questions) will be much edified. =:^) -- Duncan - List replies preferred. No HTML msgs. "Every nonfree program has a lord, a master -- and if you use the program, he is your master." Richard Stallman -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
