Ok, thanks for your replay This is a root FS, how can I defragment it? If I try to launch it I get this output: menion@Menionubuntu:~$ sudo btrfs filesystem defragment -r / ERROR: defrag failed on /bin/bash: Text file busy ERROR: defrag failed on /bin/dash: Text file busy ERROR: defrag failed on /bin/btrfs: Text file busy ERROR: defrag failed on /lib/systemd/systemd: Text file busy ERROR: defrag failed on /lib/systemd/systemd-journald: Text file busy ERROR: defrag failed on /lib/systemd/systemd-logind: Text file busy ERROR: defrag failed on /lib/systemd/systemd-resolved: Text file busy ERROR: defrag failed on /lib/systemd/systemd-timesyncd: Text file busy ERROR: defrag failed on /lib/systemd/systemd-udevd: Text file busy ERROR: defrag failed on /lib/x86_64-linux-gnu/ld-2.27.so: Text file busy Bye Il giorno mar 28 ago 2018 alle ore 13:54 Qu Wenruo <quwenruo.btrfs@xxxxxxx> ha scritto: > > > > On 2018/8/28 下午5:34, Menion wrote: > > Hi all > > I have run a distro upgrade on my Ubuntu 16.04 that runs ppa kernel > > 4.17.2 with btrfsprogs 4.17.0 > > The root filesystem is BTRFS single created by the Ubuntu Xenial > > installer (so on kernel 4.4.0) on an internal mmc, located in > > /dev/mmcblk0p3 > > After the upgrade I have cleaned apt cache and checked the free space, > > the results were odd, following some checks (shrinked), followed by > > more comments: > > > > root@Menionubuntu:/home/menion# df -h > > Filesystem Size Used Avail Use% Mounted on > > ............................................................... > > /dev/mmcblk0p3 28G 24G 2.7G 90% / > > > > root@Menionubuntu:/home/menion# btrfs fi usage /usr > > Overall: > > Device size: 27.07GiB > > Device allocated: 25.28GiB > > Device unallocated: 1.79GiB > > Device missing: 0.00B > > Used: 23.88GiB > > Free (estimated): 2.69GiB (min: 2.69GiB) > > Data ratio: 1.00 > > Metadata ratio: 1.00 > > Global reserve: 72.94MiB (used: 0.00B) > > > > Data,single: Size:24.00GiB, Used:23.10GiB > > /dev/mmcblk0p3 24.00GiB > > > > Metadata,single: Size:1.25GiB, Used:801.97MiB > > /dev/mmcblk0p3 1.25GiB > > > > System,single: Size:32.00MiB, Used:16.00KiB > > /dev/mmcblk0p3 32.00MiB > > > > Unallocated: > > /dev/mmcblk0p3 1.79GiB > > > > root@Menionubuntu:/home/menion# btrfs fi df /mnt > > Data, single: total=24.00GiB, used=23.10GiB > > System, single: total=32.00MiB, used=16.00KiB > > Metadata, single: total=1.25GiB, used=801.92MiB > > GlobalReserve, single: total=72.89MiB, used=0.00B > > > > The different ways to check the free space are coherent, but if I > > check the directories usage on root, surprise: > > > > root@Menionubuntu:/home/menion# du -x -s -h /* > > 17M /bin > > 189M /boot > > 36K /dead.letter > > 0 /dev > > 18M /etc > > 6.1G /home > > 4.0K /initrd.img > > 4.0K /initrd.img.old > > 791M /lib > > 8.3M /lib64 > > 0 /media > > 4.0K /mnt > > 0 /opt > > du: cannot access '/proc/24660/task/24660/fd/3': No such file or directory > > du: cannot access '/proc/24660/task/24660/fdinfo/3': No such file or directory > > du: cannot access '/proc/24660/fd/3': No such file or directory > > du: cannot access '/proc/24660/fdinfo/3': No such file or directory > > 0 /proc > > 2.9M /root > > 2.9M /run > > 17M /sbin > > 4.0K /snap > > 0 /srv > > 0 /sys > > 0 /tmp > > 6.1G /usr > > 2.0G /var > > 4.0K /vmlinuz > > 4.0K /vmlinuz.old > > 4.0K /webmin-setup.out > > > > The computed usage is 15Gb which is what I expected, so there are 9Gb > > lost somewhere. > > I have run scrub and then full balance with: > > I think this is related to btrfs CoW and extent booking. > > One simple example would be: > > xfs_io -f -c "pwrite 0 128k" -c "sync" -c "pwrite 0 64K" \ > /mnt/btrfs/file1 > > The result "/mnt/btrfs/file1" will only be sized 128K in du, but it > on-disk usage is 128K + 64K. > > The first 128K is the data written by the first "pwrite" command, it > caused a full 128K extent on disk. > Then the 2nd pwrite command also created a new 64K extent, which is the > default data CoW behavior. > The first half of the original 128K extent is not used by anyone, but it > still takes space. > > Above btrfs extent booking behavior could cause a lot of wasted space > even there is only one single subvolume without any snapshot. > > In that case, instead of balance, defrag should be your friend to free > up some space. > > Thanks, > Qu > > > > > btrfs scrub start / > > btrfs balance start / > > The balance freed 100Mb of space, it was running in background so I > > have checked dmesg when "btrfs balance status" said that was completed > > > > dmesg of balance: > > > > [47264.250141] BTRFS info (device mmcblk0p3): relocating block group > > 37154193408 flags system > > [47264.592082] BTRFS info (device mmcblk0p3): relocating block group > > 36046897152 flags data > > [47271.499809] BTRFS info (device mmcblk0p3): found 73 extents > > [47272.329921] BTRFS info (device mmcblk0p3): found 60 extents > > [47272.471059] BTRFS info (device mmcblk0p3): relocating block group > > 35778461696 flags metadata > > [47280.530041] BTRFS info (device mmcblk0p3): found 3199 extents > > [47280.735667] BTRFS info (device mmcblk0p3): relocating block group > > 34704719872 flags data > > [47301.460523] BTRFS info (device mmcblk0p3): relocating block group > > 37221302272 flags data > > [47306.038404] BTRFS info (device mmcblk0p3): found 5 extents > > [47306.481371] BTRFS info (device mmcblk0p3): found 5 extents > > [47306.673135] BTRFS info (device mmcblk0p3): relocating block group > > 37187747840 flags system > > [47306.874874] BTRFS info (device mmcblk0p3): found 1 extents > > [47307.073288] BTRFS info (device mmcblk0p3): relocating block group > > 34704719872 flags data > > [47371.059074] BTRFS info (device mmcblk0p3): found 16258 extents > > [47388.191208] BTRFS info (device mmcblk0p3): found 16094 extents > > [47388.985462] BTRFS info (device mmcblk0p3): relocating block group > > 31215058944 flags metadata > > [47439.164167] BTRFS info (device mmcblk0p3): found 7378 extents > > [47440.163793] BTRFS info (device mmcblk0p3): relocating block group > > 30141317120 flags data > > [47593.239048] BTRFS info (device mmcblk0p3): found 15636 extents > > [47618.389357] BTRFS info (device mmcblk0p3): found 15634 extents > > [47620.020122] BTRFS info (device mmcblk0p3): relocating block group > > 29012000768 flags data > > [47637.708444] BTRFS info (device mmcblk0p3): found 1154 extents > > [47639.757342] BTRFS info (device mmcblk0p3): found 1154 extents > > [47640.375483] BTRFS info (device mmcblk0p3): relocating block group > > 27938258944 flags data > > [47743.312441] BTRFS info (device mmcblk0p3): found 17009 extents > > [47756.928461] BTRFS info (device mmcblk0p3): found 17005 extents > > [47757.607346] BTRFS info (device mmcblk0p3): relocating block group > > 9416212480 flags metadata > > [47825.819449] BTRFS info (device mmcblk0p3): found 11503 extents > > [47826.465926] BTRFS info (device mmcblk0p3): relocating block group > > 8342470656 flags data > > [47900.754062] BTRFS info (device mmcblk0p3): found 20607 extents > > [47928.061348] BTRFS info (device mmcblk0p3): found 20607 extents > > [47929.125750] BTRFS info (device mmcblk0p3): relocating block group > > 4852809728 flags metadata > > [47993.308492] BTRFS info (device mmcblk0p3): found 13214 extents > > [47994.883308] BTRFS info (device mmcblk0p3): relocating block group > > 3779067904 flags data > > [48108.871895] BTRFS info (device mmcblk0p3): found 13256 extents > > [48124.623607] BTRFS info (device mmcblk0p3): found 13255 extents > > [48125.156150] BTRFS info (device mmcblk0p3): relocating block group > > 3510632448 flags metadata > > [48191.030178] BTRFS info (device mmcblk0p3): found 12394 extents > > [48193.202016] BTRFS info (device mmcblk0p3): relocating block group > > 2436890624 flags data > > [48347.733120] BTRFS info (device mmcblk0p3): found 22889 extents > > [48371.149135] BTRFS info (device mmcblk0p3): found 22889 extents > > [48373.723037] BTRFS info (device mmcblk0p3): relocating block group > > 20971520 flags metadata > > [48449.367016] BTRFS info (device mmcblk0p3): found 13755 extents > > [48451.058818] BTRFS info (device mmcblk0p3): relocating block group > > 12582912 flags data > > [48453.657685] BTRFS info (device mmcblk0p3): found 726 extents > > [48461.188484] BTRFS info (device mmcblk0p3): found 726 extents > > [48463.496116] BTRFS info (device mmcblk0p3): relocating block group > > 4194304 flags metadata > > [48476.405722] BTRFS info (device mmcblk0p3): found 403 extents > > [48479.254106] BTRFS info (device mmcblk0p3): 17 enospc errors during balance > > > > There is this enospc errors, can anyone help me in understanding what > > is going on? > > Bye > > >
