A ploop-based container cannot be resized with a following error:
~# vzctl set 101 --diskspace 250G --save Resize the image /vz/private/101/root.hdd to 262144000K dumpe2fs 1.41.12 (17-May-2010) Failed to resize image /vz/private/101/root.hdd: Unable to change image size to 524279808 sectors, minimal size is 795978752 Saved parameters for Container 101
However, real consumption is less than 250G:
~#vzctl exec 101 df -h Filesystem Size Used Avail Use% Mounted on /dev/ploop42782p1 196G 125G 48G 73% / tmpfs 1.0G 0 1.0G 0% /lib/init/rw tmpfs 1.0G 0 1.0G 0% /dev/shm
Container may have a huge balloon:
~# ploop-balloon show -m /vz/root/101/ Current size of hidden balloon is 69986156544 bytes
One of the possible reasons is that the container had its
diskspace limit set to a significantly greater value than it is right now, or converted from VZFS to ploop, and source container had relatively high
diskinodes limit. Such containers have filesystem with a huge space reserved for inodes table, e.g. container with 5 Tb diskspace limit will have ~70Gb reserved for the inodes table.
To resolve the issue offline resize should be performed.
Stop the container:
~# vzctl stop 101
Resize the container in offline mode:
~# vzctl set 101 --diskspace 250G --save --offline
NOTE: At least the same amount of space consumed by the container should be free on the node to perform offline resize operation.