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See the lxc-clone manpage for more information. 6.11.1. Snapshots
To more easily support the use of snapshot clones for iterative container development, LXC supports snapshots. When working on a container C1, before making a potentially dangerous or hard-to-revert change, you can create a snapshot
sudo lxc-snapshot -n C1
which is a snapshot-clone called 'snap0' under /var/lib/lxcsnaps or $HOME/.local/share/lxcsnaps. The next snapshot will be called 'snap1', etc. Existing snapshots can be listed using lxc-snapshot -L -n C1, and a snapshot can be restored - erasing the current C1 container - using lxc-snapshot -r snap1 -n C1. After the restore command, the snap1 snapshot continues to exist, and the previous C1 is erased and replaced with the snap1 snapshot.
Snapshots are supported for btrfs, lvm, zfs, and overlayfs containers. If lxc-snapshot is called on a directory- backed container, an error will be logged and the snapshot will be created as a copy-clone. The reason for this is that if the user creates an overlayfs snapshot of a directory-backed container and then makes changes to the directory-backed container, then the original container changes will be partially reflected in the snapshot. If snapshots of a directory backed container C1 are desired, then an overlayfs clone of C1 should be created, C1 should not be touched again, and the overlayfs clone can be edited and snapshotted at will, as such
lxc-clone -s -o C1 -n C2
lxc-start -n C2 -d # make some changes
lxc-stop -n C2
lxc-snapshot -n C2 lxc-start -n C2 # etc