Ploop/Backup
This article explains how to do consistent file-based backups for ploop containers, using ploop snapshot feature.
Backup types
There are two ways of doing backups, both have their pros and cons.
- When doing an image backup, one copies ploop image files directly. There can be only one big file, or maybe a few relatively big files. Copying a few big files (rather than a lot of small files) is faster because there's not too much metadata (file info) to be copied). Also, filesystem properties are fully preserving (since images containing the filesystem are copied).
- When doing a file backup, one copies individual container' files. This is more suitable if you want selective backups (such as only some directories/files).
The following table summarizes pros and cons of both approaches.
| Characteristic | Image | File |
|---|---|---|
| Incremental backups | Yes | Yes/No* |
| Selective backups | No | Yes |
| Faster full backup and restore | Yes | No |
| Preserve filesystem properties | Yes | No |
| Compatible with pre-ploop backups | No | Yes |
| Restore individual files | Yes | Yes |
Image-based backup
Assuming you have a running container identified by $CTID. The following needs to be done:
# Known snapshot ID
ID=$(uuidgen)
VE_PRIVATE=$(VEID=$CTID; source /etc/vz/vz.conf; source /etc/vz/conf/$CTID.conf; echo $VE_PRIVATE)
# Take a snapshot without suspending a CT and saving its config
vzctl snapshot $CTID --id $ID --skip-suspend --skip-config
# Perform a backup using your favorite backup tool
# (cp is just an example)
cp $VE_PRIVATE/root.hdd/* /backup/destination
# Delete (merge) the snapshot
vzctl snapshot-delete $CTID --id $IDFile-based backup
Assuming you have a running container identified by $CTID. The following needs to be done:
# Known snapshot ID
ID=$(uuidgen)
# Directory used to mount a snapshot
MNTDIR=./mnt
mkdir $MNTDIR
# Take a snapshot without suspending a CT and saving its config
vzctl snapshot $CTID --id $ID --skip-suspend --skip-config
# Mount the snapshot taken
vzctl snapshot-mount $CTID --id $ID --target $MNTDIR
# Perform a backup using your favorite backup tool
# (tar is just an example)
tar cf backup.tar.xz $MNTDIR
# Unmount the snapshot
vzctl snapshot-umount $CTID --id $ID
# Delete (merge) the snapshot
vzctl snapshot-delete $CTID --id $ID