ST posted on Mon, 20 Nov 2017 18:50:26 +0200 as excerpted: > [...] to set btrfs quota on a /home subvolume as say > 0.8*TotalCapacityOfRoot and then assign to it individual users' > subvolumes with certain (smaller) quatos. On the narrow subject of btrfs quotas... Just be sure you're aware of the effect of btrfs quotas on btrfs maintenance command times, and are using a "newish" kernel, as... * For years quotas were so buggy that they simply weren't sanely reliable (negative numbers, anyone?). In general those bugs are fixed in newer kernels, but there's still minor tweaks going in. I'd for sure want at /least/ 4.9-LTS series if I were relying on kernels (and I'm not /entirely/ sure the appropriate patches have all made it there), and would want to move to 4.14-LTS ASAP. Or just use the current kernel series and upgrade with it. IOW, don't even consider quotas pre-4.9. They're too buggy to be worth the hassle. * While the worst quota bugs now appear to be quashed and it's at least usable (the numbers come out correct), quotas continue to have scaling issues and likely will for some time to come. Generally these scaling issues don't affect generic filesystem (or quota) operation, but they *do* affect various btrfs maintenance commands where they compound already severe scaling interactions with snapshots and reflinks in commands such as btrfs subvol delete, btrfs balance (and thus btrfs device remove due to its implicit balance), and btrfs check, to the point that the commands cannot complete in practical time (days to weeks, even months, instead of hours). For commands such as btrfs balance, temporarily disabling quotas (renable and rescan if necessary when done) speeds things up dramatically, but that's not likely to be possible in many of the scenarios one would find themselves wanting to run btrfs check in. If you're already aware of and prepared to work with those caveats, great, but I've seen enough people complaining about slow balance, etc, due to having quotas enabled (and being thrilled with the actually workable speed once they turn them off) when they didn't really need them, that I tend to cringe inside every time I see people saying they plan on using them, without mentioning that they're aware of the issues and find them an acceptable tradeoff for their use-case. -- 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 majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
