+That way it is possible to store several backup in the same directory. You can
+limit the number of backups that are kept with various retention options, see
+the xref:vzdump_retention[Backup Retention] section below.
+
+Backup File Compression
+-----------------------
+
+The backup file can be compressed with one of the following algorithms: `lzo`
+footnote:[Lempel–Ziv–Oberhumer a lossless data compression algorithm
+https://en.wikipedia.org/wiki/Lempel-Ziv-Oberhumer], `gzip` footnote:[gzip -
+based on the DEFLATE algorithm https://en.wikipedia.org/wiki/Gzip] or `zstd`
+footnote:[Zstandard a lossless data compression algorithm
+https://en.wikipedia.org/wiki/Zstandard].
+
+Currently, Zstandard (zstd) is the fastest of these three algorithms.
+Multi-threading is another advantage of zstd over lzo and gzip. Lzo and gzip
+are more widely used and often installed by default.
+
+You can install pigz footnote:[pigz - parallel implementation of gzip
+https://zlib.net/pigz/] as a drop-in replacement for gzip to provide better
+performance due to multi-threading. For pigz & zstd, the amount of
+threads/cores can be adjusted. See the
+xref:vzdump_configuration[configuration options] below.
+
+The extension of the backup file name can usually be used to determine which
+compression algorithm has been used to create the backup.
+
+|===
+|.zst | Zstandard (zstd) compression
+|.gz or .tgz | gzip compression
+|.lzo | lzo compression
+|===
+
+If the backup file name doesn't end with one of the above file extensions, then
+it was not compressed by vzdump.
+
+Backup Encryption
+-----------------
+
+For Proxmox Backup Server storages, you can optionally set up client-side
+encryption of backups, see xref:storage_pbs_encryption[the corresponding section.]
+
+[[vzdump_retention]]
+Backup Retention
+----------------
+
+With the `prune-backups` option you can specify which backups you want to keep
+in a flexible manner. The following retention options are available:
+
+`keep-all <boolean>` ::
+Keep all backups. If this is `true`, no other options can be set.
+
+`keep-last <N>` ::
+Keep the last `<N>` backups.
+
+`keep-hourly <N>` ::
+Keep backups for the last `<N>` hours. If there is more than one
+backup for a single hour, only the latest is kept.
+
+`keep-daily <N>` ::
+Keep backups for the last `<N>` days. If there is more than one
+backup for a single day, only the latest is kept.
+
+`keep-weekly <N>` ::
+Keep backups for the last `<N>` weeks. If there is more than one
+backup for a single week, only the latest is kept.
+
+NOTE: Weeks start on Monday and end on Sunday. The software uses the
+`ISO week date`-system and handles weeks at the end of the year correctly.
+
+`keep-monthly <N>` ::
+Keep backups for the last `<N>` months. If there is more than one
+backup for a single month, only the latest is kept.
+
+`keep-yearly <N>` ::
+Keep backups for the last `<N>` years. If there is more than one
+backup for a single year, only the latest is kept.
+
+The retention options are processed in the order given above. Each option
+only covers backups within its time period. The next option does not take care
+of already covered backups. It will only consider older backups.
+
+Specify the retention options you want to use as a
+comma-separated list, for example:
+
+ # vzdump 777 --prune-backups keep-last=3,keep-daily=13,keep-yearly=9
+
+While you can pass `prune-backups` directly to `vzdump`, it is often more
+sensible to configure the setting on the storage level, which can be done via
+the web interface.
+
+NOTE: The old `maxfiles` option is deprecated and should be replaced either by
+`keep-last` or, in case `maxfiles` was `0` for unlimited retention, by
+`keep-all`.
+
+
+Prune Simulator
+~~~~~~~~~~~~~~~
+
+You can use the https://pbs.proxmox.com/docs/prune-simulator[prune simulator
+of the Proxmox Backup Server documentation] to explore the effect of different
+retention options with various backup schedules.
+
+Retention Settings Example
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The backup frequency and retention of old backups may depend on how often data
+changes, and how important an older state may be, in a specific work load.
+When backups act as a company's document archive, there may also be legal
+requirements for how long backups must be kept.
+
+For this example, we assume that you are doing daily backups, have a retention
+period of 10 years, and the period between backups stored gradually grows.
+
+`keep-last=3` - even if only daily backups are taken, an admin may want to
+ create an extra one just before or after a big upgrade. Setting keep-last
+ ensures this.
+
+`keep-hourly` is not set - for daily backups this is not relevant. You cover
+ extra manual backups already, with keep-last.
+
+`keep-daily=13` - together with keep-last, which covers at least one
+ day, this ensures that you have at least two weeks of backups.
+
+`keep-weekly=8` - ensures that you have at least two full months of
+ weekly backups.
+
+`keep-monthly=11` - together with the previous keep settings, this
+ ensures that you have at least a year of monthly backups.
+
+`keep-yearly=9` - this is for the long term archive. As you covered the
+ current year with the previous options, you would set this to nine for the
+ remaining ones, giving you a total of at least 10 years of coverage.
+
+We recommend that you use a higher retention period than is minimally required
+by your environment; you can always reduce it if you find it is unnecessarily
+high, but you cannot recreate backups once they have been removed.
+
+[[vzdump_protection]]
+Backup Protection
+-----------------
+
+You can mark a backup as `protected` to prevent its removal. Attempting to
+remove a protected backup via {pve}'s UI, CLI or API will fail. However, this
+is enforced by {pve} and not the file-system, that means that a manual removal
+of a backup file itself is still possible for anyone with write access to the
+underlying backup storage.
+
+NOTE: Protected backups are ignored by pruning and do not count towards the
+retention settings.
+
+For filesystem-based storages, the protection is implemented via a sentinel file
+`<backup-name>.protected`. For Proxmox Backup Server, it is handled on the
+server side (available since Proxmox Backup Server version 2.1).
+
+Use the storage option `max-protected-backups` to control how many protected
+backups per guest are allowed on the storage. Use `-1` for unlimited. The
+default is unlimited for users with `Datastore.Allocate` privilege and `5` for
+other users.
+
+[[vzdump_notes]]
+Backup Notes
+------------
+
+You can add notes to backups using the 'Edit Notes' button in the UI or via the
+storage content API.
+
+It is also possible to specify a template for generating notes dynamically for
+a backup job and for manual backup. The template string can contain variables,
+surrounded by two curly braces, which will be replaced by the corresponding
+value when the backup is executed.
+
+Currently supported are:
+
+* `{{cluster}}` the cluster name, if any
+* `{{guestname}}` the virtual guest's assigned name
+* `{{node}}` the host name of the node the backup is being created
+* `{{vmid}}` the numerical VMID of the guest
+
+When specified via API or CLI, it needs to be a single line, where newline and
+backslash need to be escaped as literal `\n` and `\\` respectively.