simfs : openvz container filesystem

OpenVZ guests get a filesystem called "simfs" for the root filesystem.

simfs is a proxy-filesystem. simfs is not an actual filesystem; it’s a map to a directory on the host (by default /vz/private/). This file system allows to isolate a particular CT from other CTs.

The /proc/mounts file in the guest VM looks like this


[root@centos32 /]# cat /proc/mounts
/dev/simfs / simfs rw,relatime 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,relatime 0 0
none /dev devtmpfs rw,relatime,mode=755 0 0
none /dev/pts devpts rw,relatime,gid=5,mode=620,ptmxmode=000 0 0
none /dev/shm tmpfs rw,relatime 0 0
none /proc/sys/fs/binfmt_misc binfmt_misc rw,relatime 0 0

The df command displays the mounted partition as follows


[root@centos32 /]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/simfs             10G  1.2G  8.9G  12% /
none                  128M  4.0K  128M   1% /dev
none                  128M     0  128M   0% /dev/shm

Can we run fsck on the simfs filesystem?

No. fsck can be run only on file systems on block devices (such as /dev/sda for example) and we cannot run fsck on proxy file system such as simfs.