As the file system gets more and more full, the free space gets more and more fragmented. This results in disastrous performance hits for files that are written when the file system gets full, and then when you later try to read them, you will suffer similar disastrous performance hits.
This is of course much more notable on HDD, but even on SSD's, a random write workload is always going to result in greater flash wear and lower performance than a sequential write workload --- particularly on the cheaper flash that you would expect to see in tablets and phones (i.e., eMMC flash) --- and even some of the crappier desktop SSD's. Now, if you have an Intel or Samsung SSD, this might not matter as much (although you will still see a performance hit) --- but having mke2fs figure out whether you have a competently implemented flash translation layer, or a spectacularly crappy one (since on phones they calculate the BOM cost down to the hundredth or thousandth of a cent, and that extra 25 cents worth of better FTL license fees and controller memory is Just Too Damn High :-), is just too much complexity to put into mke2fs's program logic. It's better to have a simple, well defined default, and then if you know for sure that you have a system where you don't mind highly fragmented files, to adjust the root reserve. As far as the server and the cloud, for the cloud, it won't really matter since guest OS's generally have relatively small amounts of space. And Ubuntu has stopped caring about the enterprise server market a long time ago. As far as the cloud host OS, there's a heck of a lot more tuning you need to do if you what a high-performing, price/performance competitive offering, such that adjusting the root reserve is the very least of your problems.... In any case, this is not something I intend to change for upstream, either in e2fsprogs or the Debian package. If the Ubuntu release engineers want to make a change, they are of course free to do so. But I wouldn't recomend it. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to e2fsprogs in Ubuntu. https://bugs.launchpad.net/bugs/1340448 Title: 5% reservation for root is inappropriate for large disks/arrays Status in “e2fsprogs” package in Ubuntu: Confirmed Bug description: mke2fs (and it's ext3 and ext4 analogs) still default to reserving 5% of the filesystem for root. With the size of modern disks and arrays this isn't a terribly sensible default, e.g. if I have a 10Tb array, mke2fs will reserve 500Gb for root. Obviously this is both tunable at FS creation time and fixable after the fact but I still think we should try and improve the defaults. Given the size of modern disks, I think it'd make sense to either a) only reserve a smaller amount (e.g. 1%) or b) reserve n% if the filesystem is << NNN GB and otherwise reserve NN GB. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/e2fsprogs/+bug/1340448/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
