thanks for the explanation 2015-12-18 15:49 GMT+03:00 Henk Slager <eye...@gmail.com>: > On Fri, Dec 18, 2015 at 10:37 AM, Timofey Titovets <nefelim...@gmail.com> > wrote: >> Hi guys, i catch strange problem: >> btrfs with mysql, mysql rewrite data, but space consumption only increasing >> i.e: >> >> df -h >> /dev/sdb1 112G 73G 39G 66% /var/lib/mysql >> >> du -hs >> 43G /var/lib/mysql/ > As the fs is new, the file(s) in this directory might initially have > large extents. Writing a lot to the file(s), with larger pieces at > file-offsets that belong to those large extents makes btrfs CoW > allocate new extents but does not free the original space in the large > extents (no extent splitting in btrfs). > > You could run: > # filefrag -k -v /var/lib/mysql/* > to see what the situation is, but migh be too much data. > In theory, if you would read and writeback the full offset+size of the > larger extents, the original large extent space is freed. You get more > fragmentation then, but should not be big problem on SSD (if > /dev/sdb1 is that) > > File(s) re-creating with nodatacow mount option on might also be your > choice. And make sure you have no hidden snapshots somewhere, but I > assume you have checked that. > Another brute-force work-around would be to run: > # btrfs fi defrag -r -v -clzo /var/lib/mysql/ > so to force rewriting info smaller extents, but you probably don't > want compression on those file(s) > >> btrfs fi df /var/lib/mysql >> Data, single: total=78.00GiB, used=72.39GiB >> System, single: total=32.00MiB, used=16.00KiB >> Metadata, single: total=1.00GiB, used=109.61MiB >> GlobalReserve, single: total=48.00MiB, used=0.00B >> >> This is fresh fs (seven hours old) >> Created by btrfs-progs 4.1.2 >> Linux 4.2.0-0.bpo.1-amd64 #1 SMP Debian 4.2.6-3~bpo8+2 (2015-12-14) >> x86_64 GNU/Linux >> >> Btrfsck not found any errors on this device >> >> P.S. First i think what it because system have opened files >> descriptors, but after reboot, space not return >> If i write file by dd and after delete it, space will returned (with >> direct io and without) >> >> -- >> Have a nice day, >> Timofey. >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in >> the body of a message to majord...@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- > To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
-- Have a nice day, Timofey. -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
