Editing Ploop/Backup

[[File:Ploop-backup.png|300px|right|thumb|How backup via snapshot is done]]
This article explains how to do consistent backups for [[ploop]] containers, using ploop snapshot feature.

== Types of backup ==
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.

{| class="wikitable"
! Characteristic
! Image
! File
|-
|| Incremental backups
| {{Yes}} || {{Yes-No}}{{H:title|Requires tools such as rsnapshot|<sup>*</sup>}}
|-
|| Selective backups
| {{No}} || {{Yes}}
|-
|| Faster full backup and restore
| {{Yes}} || {{No}}
|-
| Preserve filesystem properties
| {{Yes}} || {{No}}
|-
|| Compatible with pre-ploop backups
| {{Yes-No}}{{H:title|It's always possible to create a new, same-size ploop device and then restore the files into the mounted ploop partition|<sup>*</sup>}} || {{Yes}}
|-
|| Restore individual files
| {{Yes}} || {{Yes}}
|}

== Image-based backups ==

Assuming you have a running container identified by <code>$CTID</code>. The following needs to be done:

<source lang="bash">
# Known snapshot ID
ID=$(uuidgen)
VE_PRIVATE=$(vzlist -H -o private $CTID)

# 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 $ID
</source>

The following script implements the commands above and allows - when stored as <code>vzbackup</code> - to backup your container by executing the script in the following way:

<code>./vzbackup 101 /backup/destination/</code>

The script removes older backups and keeps only the latest four backups. You can change the number of backups kept by changing the four in <code>head -n-4</code> to the number of backups you would like to keep.

<source lang="bash">
#!/bin/bash
if [ -z $1 -o -z $2 ]
then
	echo "Usage: vzbackup CTID BACKUP-PATH"
	exit 1
fi

CTID=$1
FOLDER=$2
BACKUPPATH=$FOLDER/$CTID-$( date +%F_%H_%M )

#create BACKUP-PATH
mkdir -p $BACKUPPATH

# Known snapshot ID
ID=$(uuidgen)
VE_PRIVATE=$(vzlist -H -o private $CTID)
 
# 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/* $BACKUPPATH/
 
# Delete (merge) the snapshot
vzctl snapshot-delete $CTID --id $ID

# remove old backups
rm -rf $( find $FOLDER -type d -name "$CTID*" -exec ls -d1rt "{}" + | head -n-4  )

echo "BACKUP FINISHED."
</source>

== File-based backup ==

Assuming you have a running container identified by <code>$CTID</code>. The following needs to be done:

<source lang="bash">
# 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 $MNTDIR

# tar with compression examples, see man page of tar for more options
# tar cfJ backup.tar.xz $MNTDIR
# tar cfz backup.tar.gz $MNTDIR

# Unmount the snapshot
vzctl snapshot-umount $CTID --id $ID

# Delete (merge) the snapshot
vzctl snapshot-delete $CTID --id $ID
</source>

== See also ==

* [[Ploop]]
* [[Man/vzctl.8#Snapshotting|vzctl(8), section Snapshotting]].

[[Category: Storage]]
[[Category: HOWTO]]