On 2017年12月02日 10:21, Tomasz Pala wrote: > On Sat, Dec 02, 2017 at 09:47:19 +0800, Qu Wenruo wrote: > >>> Actually I should rephrase the problem: >>> >>> "snapshot has taken 8 GB of space despite nothing has altered source >>> subvolume" > > Actually, after: > > # btrfs balance start -v -dconvert=raid1 / > ctrl-c on block group 35G/113G > # btrfs balance start -v -dconvert=raid1,soft / > # btrfs balance start -v -dusage=55 / > Done, had to relocate 1 out of 56 chunks > # btrfs balance start -v -musage=55 / > Done, had to relocate 2 out of 55 chunks > > and waiting a few minutes after ...the 8 GB I've lost yesterday is back: > > # btrfs fi sh / > Label: none uuid: 17a3de25-6e26-4b0b-9665-ac267f6f6c4a > Total devices 2 FS bytes used 44.10GiB > devid 1 size 64.00GiB used 54.00GiB path /dev/sda2 > devid 2 size 64.00GiB used 54.00GiB path /dev/sdb2 > > # btrfs fi usage / > Overall: > Device size: 128.00GiB > Device allocated: 108.00GiB > Device unallocated: 20.00GiB > Device missing: 0.00B > Used: 88.19GiB > Free (estimated): 18.75GiB (min: 18.75GiB) > Data ratio: 2.00 > Metadata ratio: 2.00 > Global reserve: 131.14MiB (used: 0.00B) > > Data,RAID1: Size:51.97GiB, Used:43.22GiB > /dev/sda2 51.97GiB > /dev/sdb2 51.97GiB > > Metadata,RAID1: Size:2.00GiB, Used:895.69MiB > /dev/sda2 2.00GiB > /dev/sdb2 2.00GiB > > System,RAID1: Size:32.00MiB, Used:16.00KiB > /dev/sda2 32.00MiB > /dev/sdb2 32.00MiB > > Unallocated: > /dev/sda2 10.00GiB > /dev/sdb2 10.00GiB > > # btrfs dev usage / > /dev/sda2, ID: 1 > Device size: 64.00GiB > Device slack: 0.00B > Data,RAID1: 51.97GiB > Metadata,RAID1: 2.00GiB > System,RAID1: 32.00MiB > Unallocated: 10.00GiB > > /dev/sdb2, ID: 2 > Device size: 64.00GiB > Device slack: 0.00B > Data,RAID1: 51.97GiB > Metadata,RAID1: 2.00GiB > System,RAID1: 32.00MiB > Unallocated: 10.00GiB > > # btrfs fi df / > Data, RAID1: total=51.97GiB, used=43.22GiB > System, RAID1: total=32.00MiB, used=16.00KiB > Metadata, RAID1: total=2.00GiB, used=895.69MiB > GlobalReserve, single: total=131.14MiB, used=0.00B > > # df > /dev/sda2 64G 45G 19G 71% / > > However the difference is on active root fs: > > -0/291 24.29GiB 9.77GiB > +0/291 15.99GiB 76.00MiB > > Still, 45G used, while there is (if I counted this correctly) 25G of data... > >> Then please provide correct qgroup numbers. >> >> The correct number should be get by: >> # btrfs quota enable <mnt> >> # btrfs quota rescan -w <mnt> >> # btrfs qgroup show -prce --sync <mnt> > > OK, just added the --sort=excl: > > qgroupid rfer excl max_rfer max_excl parent child > -------- ---- ---- -------- -------- ------ ----- > 0/5 16.00KiB 16.00KiB none none --- --- > 0/361 22.57GiB 7.00MiB none none --- --- > 0/358 22.54GiB 7.50MiB none none --- --- > 0/343 22.36GiB 7.84MiB none none --- --- > 0/345 22.49GiB 8.05MiB none none --- --- > 0/357 22.50GiB 9.27MiB none none --- --- > 0/360 22.57GiB 10.27MiB none none --- --- > 0/344 22.48GiB 11.09MiB none none --- --- > 0/359 22.55GiB 12.57MiB none none --- --- > 0/362 22.59GiB 22.96MiB none none --- --- > 0/302 12.87GiB 31.23MiB none none --- --- > 0/428 15.96GiB 38.68MiB none none --- --- > 0/294 11.09GiB 47.86MiB none none --- --- > 0/336 21.80GiB 49.59MiB none none --- --- > 0/300 12.56GiB 51.43MiB none none --- --- > 0/342 22.31GiB 52.93MiB none none --- --- > 0/333 21.71GiB 54.54MiB none none --- --- > 0/363 22.63GiB 58.83MiB none none --- --- > 0/370 23.27GiB 59.46MiB none none --- --- > 0/305 13.01GiB 61.47MiB none none --- --- > 0/331 21.61GiB 61.49MiB none none --- --- > 0/334 21.78GiB 62.95MiB none none --- --- > 0/306 13.04GiB 64.11MiB none none --- --- > 0/304 12.96GiB 64.90MiB none none --- --- > 0/303 12.94GiB 68.39MiB none none --- --- > 0/367 23.20GiB 68.52MiB none none --- --- > 0/366 23.22GiB 69.79MiB none none --- --- > 0/364 22.63GiB 72.03MiB none none --- --- > 0/285 10.78GiB 75.95MiB none none --- --- > 0/291 15.99GiB 76.24MiB none none --- --- <- > this one (default rootfs) got fixed > 0/323 21.35GiB 95.85MiB none none --- --- > 0/369 23.26GiB 96.12MiB none none --- --- > 0/324 21.36GiB 104.46MiB none none --- --- > 0/327 21.36GiB 115.42MiB none none --- --- > 0/368 23.27GiB 118.25MiB none none --- --- > 0/295 11.20GiB 148.59MiB none none --- --- > 0/298 12.38GiB 283.41MiB none none --- --- > 0/260 12.25GiB 3.22GiB none none --- --- <- > 170712, initial snapshot, OK > 0/312 17.54GiB 4.56GiB none none --- --- <- > 170811, definitely less excl > 0/388 21.69GiB 7.16GiB none none --- --- <- > this one has <100M exclusive > > > So the one block of data was released, but there are probably two more > stuck here. If the 4.5G and 7G were freed I would have 45-4.5-7=33G used, > which would agree with the 25G of data I've counted manually. > > Any ideas how to look inside these two snapshots?
I would try du first to locate the largest file. Then use use "btrfs fi du" to ensure it's not shared. (If it's not shared in "fi du" it must be exclusive to qgroup) Although this will not work as expected if it's not a large file but tons of small files. Another method is to use the send output you get. Use "btrfs receive --dump" to get a comprehensive view of what's the different between two different snapshots. Since you have already showed the size of the snapshots, which hardly goes beyond 1G, it may be possible that extent booking is the cause. And considering it's all exclusive, defrag may help in this case. Thanks, Qu > >> Rescan and --sync are important to get the correct number. >> (while rescan can take a long long time to finish) > > # time btrfs quota rescan -w / > quota rescan started > btrfs quota rescan -w / 0.00s user 0.00s system 0% cpu 30.798 total> >> And further more, please ensure that all deleted files are really deleted. >> Btrfs delay file and subvolume deletion, so you may need to sync several >> times or use "btrfs subv sync" to ensure deleted files are deleted. > > Yes, I was aware about that. However I've never had to wait after rebalance... > > regards, >
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