looking at df -h, I realized I have this /dev/loop0 mounted on /snap/core/3604 and it's always 100% full :
root@maxipc:~# df -h Filesystem Size Used Avail Use% Mounted on udev 7.8G 0 7.8G 0% /dev tmpfs 1.6G 9.9M 1.6G 1% /run /dev/sda3 116G 38G 73G 35% / tmpfs 7.8G 20M 7.8G 1% /dev/shm tmpfs 5.0M 4.0K 5.0M 1% /run/lock tmpfs 7.8G 0 7.8G 0% /sys/fs/cgroup /dev/loop0 84M 84M 0 100% /snap/core/3604 /dev/sda1 239M 111M 111M 50% /boot cgmfs 100K 0 100K 0% /run/cgmanager/fs tmpfs 1.6G 44K 1.6G 1% /run/user/1000
When I do a umount /snap/core/3604orumount /dev/loop0 it will unmount so it's apparently not busy at all(also when i try to remount /dev/loop0 again, it doesnt remount because, of course, it's not in fstab. in it, it looks like there is a whole little, cute and tiny root filesystem squashed in that 84M:
root@maxipc:~# ls -la /snap/core/3604 total 4 drwxr-xr-x 24 root root 333 Nov 30 12:39 . drwxr-xr-x 3 root root 4096 Dec 26 20:29 .. drwxr-xr-x 2 root root 1937 Nov 30 12:38 bin drwxr-xr-x 6 root root 129 Nov 30 12:38 boot drwxr-xr-x 4 root root 1160 Nov 30 12:38 dev drwxr-xr-x 80 root root 2399 Nov 30 12:38 etc drwxr-xr-x 2 root root 3 Apr 12 2016 home drwxr-xr-x 20 root root 406 Nov 30 12:38 lib drwxr-xr-x 2 root root 43 Nov 30 12:38 lib64 drwxr-xr-x 2 root root 3 Nov 30 12:35 media drwxr-xr-x 3 root root 45 Nov 30 12:39 meta drwxr-xr-x 2 root root 3 Nov 30 12:35 mnt drwxr-xr-x 2 root root 3 Nov 30 12:35 opt drwxr-xr-x 2 root root 3 Apr 12 2016 proc drwx------ 2 root root 46 Nov 30 12:38 root drwxr-xr-x 8 root root 115 Nov 30 12:38 run drwxr-xr-x 2 root root 2349 Nov 30 12:38 sbin drwxr-xr-x 2 root root 58 Nov 30 12:39 snap drwxr-xr-x 2 root root 3 Nov 30 12:35 srv drwxr-xr-x 2 root root 3 Feb 5 2016 sys drwxrwxrwt 2 root root 3 Nov 30 12:37 tmp drwxr-xr-x 11 root root 151 Nov 30 12:38 usr drwxr-xr-x 12 root root 172 Nov 30 12:38 var drwxr-xr-x 2 root root 3 Nov 30 12:36 writable
and when I try to do a fuser -m /snap/core/3604 to see who uses the mount, nothing shows up. it reappears every single boot, and I don't know how the heck it's coming up, oh also, there is no sign of it in /etc/fstab. it's also squashfs file system. it looks like it's harmless but I just wanna know why it does what it does. what is it? any help/reply would be appreciated.
Thank you in advance,
MG
ps: I thought this question is different because the loop device is mounted as if it is an primary and working filesystem eventhough it's not busy at all. it gets umounted everytime if you want to, but it shows up again after boot. usually loop devices come up by df -H but for me this loop device comes up even among things that gnome graphical tools show, just like how a hardrive shows in your nautilus.
