Backup Client Usage

The command line client for Proxmox Backup Server is called proxmox-backup-client.

Backup Repository Locations

The client uses the following format to specify a datastore repository on the backup server (where username is specified in the form of user@realm):

[[username@]server[:port]:]datastore

The default value for username is root@pam. If no server is specified, the default is the local host (localhost).

You can specify a port if your backup server is only reachable on a non-default port (for example, with NAT and port forwarding configurations).

Note that if the server uses an IPv6 address, you have to write it with square brackets (for example, [fe80::01]).

You can pass the repository with the --repository command line option, or by setting the PBS_REPOSITORY environment variable.

Below are some examples of valid repositories and their corresponding real values:

Example	User	Host:Port	Datastore
mydatastore	root@pam	localhost:8007	mydatastore
myhostname:mydatastore	root@pam	myhostname:8007	mydatastore
user@pbs@myhostname:mydatastore	user@pbs	myhostname:8007	mydatastore
user@pbs!token@host:store	user@pbs!token	host:8007	store
192.168.55.55:1234:mydatastore	root@pam	192.168.55.55:1234	mydatastore
[ff80::51]:mydatastore	root@pam	[ff80::51]:8007	mydatastore
[ff80::51]:1234:mydatastore	root@pam	[ff80::51]:1234	mydatastore

Environment Variables

PBS_REPOSITORY

The default backup repository.

PBS_PASSWORD

When set, this value is used as the password for the backup server. You can also set this to an API token secret.

PBS_PASSWORD_FD, PBS_PASSWORD_FILE, PBS_PASSWORD_CMD

Like PBS_PASSWORD, but read data from an open file descriptor, a file name or from the stdout of a command, respectively. The first defined environment variable from the order above is preferred.

PBS_ENCRYPTION_PASSWORD

When set, this value is used to access the secret encryption key (if protected by password).

PBS_ENCRYPTION_PASSWORD_FD, PBS_ENCRYPTION_PASSWORD_FILE, PBS_ENCRYPTION_PASSWORD_CMD

Like PBS_ENCRYPTION_PASSWORD, but read data from an open file descriptor, a file name or from the stdout of a command, respectively. The first defined environment variable from the order above is preferred.

PBS_FINGERPRINT

When set, this value is used to verify the server certificate (only used if the system CA certificates cannot validate the certificate).

ALL_PROXY

When set, the client uses the specified HTTP proxy for all connections to the backup server. Currently only HTTP proxies are supported. Valid proxy configurations have the following format: [http://][user:password@]<host>[:port]. Default port is 1080, if not otherwise specified.

Note

The recommended solution for shielding hosts is using tunnels such as wireguard, instead of using an HTTP proxy.

Note

Passwords must be valid UTF-8 and may not contain newlines. For your convenience, Proxmox Backup Server only uses the first line as password, so you can add arbitrary comments after the first newline.

Output Format

Most commands that produce output support the --output-format parameter. This accepts the following values:

text

Text format (default). Structured data is rendered as a table.

json

JSON (single line).

json-pretty

JSON (multiple lines, nicely formatted).

Also, the following environment variables can modify output behavior:

PROXMOX_OUTPUT_FORMAT

Defines the default output format.

PROXMOX_OUTPUT_NO_BORDER

If set (to any value), do not render table borders.

PROXMOX_OUTPUT_NO_HEADER

If set (to any value), do not render table headers.

Note

The text format is designed to be human readable, and not meant to be parsed by automation tools. Please use the json format if you need to process the output.

Creating Backups

This section explains how to create a backup from within the machine. This can be a physical host, a virtual machine, or a container. Such backups may contain file and image archives. There are no restrictions in this case.

Note

If you want to backup virtual machines or containers on Proxmox VE, see Proxmox VE Integration.

For the following example, you need to have a backup server set up, have working credentials, and know the repository name. In the following examples, we use backup-server:store1.

# proxmox-backup-client backup root.pxar:/ --repository backup-server:store1
Starting backup: host/elsa/2019-12-03T09:35:01Z
Client name: elsa
skip mount point: "/boot/efi"
skip mount point: "/dev"
skip mount point: "/run"
skip mount point: "/sys"
Uploaded 12129 chunks in 87 seconds (564 MB/s).
End Time: 2019-12-03T10:36:29+01:00

This will prompt you for a password, then upload a file archive named root.pxar containing all the files in the / directory.

Caution

Please note that proxmox-backup-client does not automatically include mount points. Instead, you will see a short skip mount point message for each of them. The idea is to create a separate file archive for each mounted disk. You can explicitly include them using the --include-dev option (i.e. --include-dev /boot/efi). You can use this option multiple times for each mount point that should be included.

The --repository option can get quite long and is used by all commands. You can avoid having to enter this value by setting the environment variable PBS_REPOSITORY. Note that if you would like this to remain set over multiple sessions, you should instead add the below line to your .bashrc file.

# export PBS_REPOSITORY=backup-server:store1

After this, you can execute all commands without having to specify the --repository option.

A single backup is allowed to contain more than one archive. For example, if you want to back up two disks mounted at /mnt/disk1 and /mnt/disk2:

# proxmox-backup-client backup disk1.pxar:/mnt/disk1 disk2.pxar:/mnt/disk2

This creates a backup of both disks.

If you want to use a namespace for the backup target, you can add the --ns parameter:

# proxmox-backup-client backup disk1.pxar:/mnt/disk1 disk2.pxar:/mnt/disk2 --ns a/b/c

The backup command takes a list of backup specifications, which include the archive name on the server, the type of the archive, and the archive source at the client. The format is:

<archive-name>.<type>:<source-path>

Common types are .pxar for file archives and .img for block device images. To create a backup of a block device, run the following command:

# proxmox-backup-client backup mydata.img:/dev/mylvm/mydata

Excluding Files/Directories from a Backup

Sometimes it is desired to exclude certain files or directories from a backup archive. To tell the Proxmox Backup client when and how to ignore files and directories, place a text file named .pxarexclude in the filesystem hierarchy. Whenever the backup client encounters such a file in a directory, it interprets each line as a glob match pattern for files and directories that are to be excluded from the backup.

The file must contain a single glob pattern per line. Empty lines and lines starting with # (indicating a comment) are ignored. A ! at the beginning of a line reverses the glob match pattern from an exclusion to an explicit inclusion. This makes it possible to exclude all entries in a directory except for a few single files/subdirectories. Lines ending in / match only on directories. The directory containing the .pxarexclude file is considered to be the root of the given patterns. It is only possible to match files in this directory and its subdirectories.

Note

Patterns without a leading / will also match in subdirectories, while patterns with a leading / will only match in the current directory.

\ is used to escape special glob characters. ? matches any single character. * matches any character, including an empty string. ** is used to match current directory and subdirectories. For example, with the pattern **/*.tmp, it would exclude all files ending in .tmp within a directory and its subdirectories. [...] matches a single character from any of the provided characters within the brackets. [!...] does the complementary and matches any single character not contained within the brackets. It is also possible to specify ranges with two characters separated by -. For example, [a-z] matches any lowercase alphabetic character, and [0-9] matches any single digit.

The order of the glob match patterns defines whether a file is included or excluded, that is to say, later entries override earlier ones. This is also true for match patterns encountered deeper down the directory tree, which can override a previous exclusion.

Note

Excluded directories will not be read by the backup client. Thus, a .pxarexclude file in an excluded subdirectory will have no effect. .pxarexclude files are treated as regular files and will be included in the backup archive.

For example, consider the following directory structure:

# ls -aR folder
folder/:
.  ..  .pxarexclude  subfolder0  subfolder1

folder/subfolder0:
.  ..  file0  file1  file2  file3  .pxarexclude

folder/subfolder1:
.  ..  file0  file1  file2  file3

The different .pxarexclude files contain the following:

# cat folder/.pxarexclude
/subfolder0/file1
/subfolder1/*
!/subfolder1/file2

# cat folder/subfolder0/.pxarexclude
file3

This would exclude file1 and file3 in subfolder0 and all of subfolder1 except file2.

Restoring this backup will result in:

ls -aR restored
restored/:
.  ..  .pxarexclude  subfolder0  subfolder1

restored/subfolder0:
.  ..  file0  file2  .pxarexclude

restored/subfolder1:
.  ..  file2

Encryption

Proxmox Backup supports client-side encryption with AES-256 in GCM mode. To set this up, you first need to create an encryption key:

# proxmox-backup-client key create my-backup.key
Encryption Key Password: **************

The key is password protected by default. If you do not need this extra protection, you can also create it without a password:

# proxmox-backup-client key create /path/to/my-backup.key --kdf none

Having created this key, it is now possible to create an encrypted backup, by passing the --keyfile parameter, with the path to the key file.

# proxmox-backup-client backup etc.pxar:/etc --keyfile /path/to/my-backup.key
Password: *********
Encryption Key Password: **************
...

Note

If you do not specify the name of the backup key, the key will be created in the default location ~/.config/proxmox-backup/encryption-key.json. proxmox-backup-client will also search this location by default, in case the --keyfile parameter is not specified.

You can avoid entering the passwords by setting the environment variables PBS_PASSWORD and PBS_ENCRYPTION_PASSWORD.

Using a Master Key to Store and Recover Encryption Keys

You can also use proxmox-backup-client key to create an RSA public/private key pair, which can be used to store an encrypted version of the symmetric backup encryption key alongside each backup and recover it later.

To set up a master key:

1. Create an encryption key for the backup:

   # proxmox-backup-client key create
   creating default key at: "~/.config/proxmox-backup/encryption-key.json"
   Encryption Key Password: **********
   ...
   

   The resulting file will be saved to ~/.config/proxmox-backup/encryption-key.json.

2. Create an RSA public/private key pair:

   # proxmox-backup-client key create-master-key
   Master Key Password: *********
   ...
   

   This will create two files in your current directory, master-public.pem and master-private.pem.

3. Import the newly created master-public.pem public certificate, so that proxmox-backup-client can find and use it upon backup.

   # proxmox-backup-client key import-master-pubkey /path/to/master-public.pem
   Imported public master key to "~/.config/proxmox-backup/master-public.pem"
   

4. With all these files in place, run a backup job:

   # proxmox-backup-client backup etc.pxar:/etc
   

   The key will be stored in your backup, under the name rsa-encrypted.key.

   Note

   The --keyfile parameter can be excluded, if the encryption key is in the default path. If you specified another path upon creation, you must pass the --keyfile parameter.

5. To test that everything worked, you can restore the key from the backup:

   # proxmox-backup-client restore /path/to/backup/ rsa-encrypted.key /path/to/target
   

   Note

   You should not need an encryption key to extract this file. However, if a key exists at the default location (~/.config/proxmox-backup/encryption-key.json) the program will prompt you for an encryption key password. Simply moving encryption-key.json out of this directory will fix this issue.

6. Then, use the previously generated master key to decrypt the file:

   # proxmox-backup-client key import-with-master-key /path/to/target --master-keyfile /path/to/master-private.pem --encrypted-keyfile /path/to/rsa-encrypted.key
   Master Key Password: ******
   New Password: ******
   Verify Password: ******
   

7. The target file will now contain the encryption key information in plain text. The success of this can be confirmed by passing the resulting json file, with the --keyfile parameter, when decrypting files from the backup.

Warning

Without their key, backed up files will be inaccessible. Thus, you should keep keys ordered and in a place that is separate from the contents being backed up. It can happen, for example, that you back up an entire system, using a key on that system. If the system then becomes inaccessible for any reason and needs to be restored, this will not be possible, as the encryption key will be lost along with the broken system.

It is recommended that you keep your master key safe, but easily accessible, in order for quick disaster recovery. For this reason, the best place to store it is in your password manager, where it is immediately recoverable. As a backup to this, you should also save the key to a USB drive and store that in a secure place. This way, it is detached from any system, but is still easy to recover from, in case of emergency. Finally, in preparation for the worst case scenario, you should also consider keeping a paper copy of your master key locked away in a safe place. The paperkey subcommand can be used to create a QR encoded version of your master key. The following command sends the output of the paperkey command to a text file, for easy printing.

proxmox-backup-client key paperkey --output-format text > qrkey.txt

Restoring Data

The regular creation of backups is a necessary step in avoiding data loss. More importantly, however, is the restoration. It is good practice to perform periodic recovery tests to ensure that you can access the data in case of disaster.

First, you need to find the snapshot which you want to restore. The snapshot list command provides a list of all the snapshots on the server:

# proxmox-backup-client snapshot list
┌────────────────────────────────┬─────────────┬────────────────────────────────────┐
│ snapshot                       │        size │ files                              │
╞════════════════════════════════╪═════════════╪════════════════════════════════════╡
│ host/elsa/2019-12-03T09:30:15Z │ 51788646825 │ root.pxar catalog.pcat1 index.json │
├────────────────────────────────┼─────────────┼────────────────────────────────────┤
│ host/elsa/2019-12-03T09:35:01Z │ 51790622048 │ root.pxar catalog.pcat1 index.json │
├────────────────────────────────┼─────────────┼────────────────────────────────────┤
...

Tip

List will by default only output the backup snapshots of the root namespace itself. To list backups from another namespace use the --ns <ns> option

You can inspect the catalog to find specific files.

# proxmox-backup-client catalog dump host/elsa/2019-12-03T09:35:01Z
...
d "./root.pxar.didx/etc/cifs-utils"
l "./root.pxar.didx/etc/cifs-utils/idmap-plugin"
d "./root.pxar.didx/etc/console-setup"
...

The restore command lets you restore a single archive from the backup.

# proxmox-backup-client restore host/elsa/2019-12-03T09:35:01Z root.pxar /target/path/

To get the contents of any archive, you can restore the index.json file in the repository to the target path '-'. This will dump the contents to the standard output.

# proxmox-backup-client restore host/elsa/2019-12-03T09:35:01Z index.json -

Interactive Restores

If you only want to restore a few individual files, it is often easier to use the interactive recovery shell.

# proxmox-backup-client catalog shell host/elsa/2019-12-03T09:35:01Z root.pxar
Starting interactive shell
pxar:/ > ls
bin        boot       dev        etc        home       lib        lib32
...

The interactive recovery shell is a minimal command line interface that utilizes the metadata stored in the catalog to quickly list, navigate and search for files in a file archive. To restore files, you can select them individually or match them with a glob pattern.

Using the catalog for navigation reduces the overhead considerably because only the catalog needs to be downloaded and, optionally, decrypted. The actual chunks are only accessed if the metadata in the catalog is insufficient or for the actual restore.

Similar to common UNIX shells, cd and ls are the commands used to change working directory and list directory contents in the archive. pwd shows the full path of the current working directory with respect to the archive root.

The ability to quickly search the contents of the archive is a commonly required feature. That's where the catalog is most valuable. For example:

pxar:/ > find etc/**/*.txt --select
"/etc/X11/rgb.txt"
pxar:/ > list-selected
etc/**/*.txt
pxar:/ > restore-selected /target/path
...

This will find and print all files ending in .txt located in etc/ or its subdirectories, and add the corresponding pattern to the list for subsequent restores. list-selected shows these patterns and restore-selected finally restores all files in the archive matching the patterns to /target/path on the local host. This will scan the whole archive.

The restore command can be used to restore all the files contained within the backup archive. This is most helpful when paired with the --pattern <glob> option, as it allows you to restore all files matching a specific pattern. For example, if you wanted to restore configuration files located in /etc, you could do the following:

pxar:/ > restore target/ --pattern etc/**/*.conf
...

The above will scan through all the directories below /etc and restore all files ending in .conf.

Mounting of Archives via FUSE

The FUSE implementation for the pxar archive allows you to mount a file archive as a read-only filesystem to a mount point on your host.

# proxmox-backup-client mount host/backup-client/2020-01-29T11:29:22Z root.pxar /mnt/mountpoint
# ls /mnt/mountpoint
bin   dev  home  lib32  libx32      media  opt   root  sbin  sys  usr
boot  etc  lib   lib64  lost+found  mnt    proc  run   srv   tmp  var

This allows you to access the full contents of the archive in a seamless manner.

Note

As the FUSE connection needs to fetch and decrypt chunks from the backup server's datastore, this can cause some additional network and CPU load on your host, depending on the operations you perform on the mounted filesystem.

To unmount the filesystem, use the umount command on the mount point:

# umount /mnt/mountpoint

Login and Logout

The client tool prompts you to enter the login password as soon as you want to access the backup server. The server checks your credentials and responds with a ticket that is valid for two hours. The client tool automatically stores that ticket and uses it for further requests to this server.

You can also manually trigger this login/logout using the login and logout commands:

# proxmox-backup-client login
Password: **********

To remove the ticket, issue a logout:

# proxmox-backup-client logout

Changing the Owner of a Backup Group

By default, the owner of a backup group is the user which was used to originally create that backup group (or in the case of sync jobs, root@pam). This means that if a user mike@pbs created a backup, another user john@pbs can not be used to create backups in that same backup group. In case you want to change the owner of a backup, you can do so with the below command, using a user that has Datastore.Modify privileges on the datastore.

# proxmox-backup-client change-owner vm/103 john@pbs

This can also be done from within the web interface, by navigating to the Content section of the datastore that contains the backup group and selecting the user icon under the Actions column. Common cases for this could be to change the owner of a sync job from root@pam, or to repurpose a backup group.

Pruning and Removing Backups

You can manually delete a backup snapshot using the forget command:

# proxmox-backup-client snapshot forget <snapshot>

Caution

This command removes all archives in this backup snapshot. They will be inaccessible and unrecoverable.

Don't forget to add the namespace --ns parameter if you want to forget a snapshot that is contained in the root namespace:

# proxmox-backup-client snapshot forget <snapshot> --ns <ns>

Although manual removal is sometimes required, the prune command is normally used to systematically delete older backups. Prune lets you specify which backup snapshots you want to keep. The following retention options are available:

--keep-last <N>

Keep the last <N> backup snapshots.

--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.

Unfinished and incomplete backups will be removed by the prune command unless they are newer than the last successful backup. In this case, the last failed backup is retained.

# proxmox-backup-client prune <group> --keep-daily 7 --keep-weekly 4 --keep-monthly 3

You can use the --dry-run option to test your settings. This only shows the list of existing snapshots and what actions prune would take.

# proxmox-backup-client prune host/elsa --dry-run --keep-daily 1 --keep-weekly 3
┌────────────────────────────────┬──────┐
│ snapshot                       │ keep │
╞════════════════════════════════╪══════╡
│ host/elsa/2019-12-04T13:20:37Z │    1 │
├────────────────────────────────┼──────┤
│ host/elsa/2019-12-03T09:35:01Z │    0 │
├────────────────────────────────┼──────┤
│ host/elsa/2019-11-22T11:54:47Z │    1 │
├────────────────────────────────┼──────┤
│ host/elsa/2019-11-21T12:36:25Z │    0 │
├────────────────────────────────┼──────┤
│ host/elsa/2019-11-10T10:42:20Z │    1 │
└────────────────────────────────┴──────┘

Note

Neither the prune command nor the forget command free space in the chunk-store. The chunk-store still contains the data blocks. To free space you need to perform Garbage Collection.

It is also possible to protect single snapshots from being pruned or deleted:

# proxmox-backup-client snapshot protected update <snapshot> true

This will set the protected flag on the snapshot and prevent pruning or manual deletion of this snapshot until the flag is removed again with:

# proxmox-backup-client snapshot protected update <snapshot> false

When a group with a protected snapshot is deleted, only the non-protected ones are removed, and the rest will remain.

Note

This flag will not be synced when using pull or sync jobs. If you want to protect a synced snapshot, you have to do this again manually on the target backup server.

Garbage Collection

The prune command removes only the backup index files, not the data from the datastore. This task is left to the garbage collection command. It is recommended to carry out garbage collection on a regular basis.

The garbage collection works in two phases. In the first phase, all data blocks that are still in use are marked. In the second phase, unused data blocks are removed.

Note

This command needs to read all existing backup index files and touches the complete chunk-store. This can take a long time depending on the number of chunks and the speed of the underlying disks.

Note

The garbage collection will only remove chunks that haven't been used for at least one day (exactly 24h 5m). This grace period is necessary because chunks in use are marked by touching the chunk which updates the atime (access time) property. Filesystems are mounted with the relatime option by default. This results in a better performance by only updating the atime property if the last access has been at least 24 hours ago. The downside is that touching a chunk within these 24 hours will not always update its atime property.

Chunks in the grace period will be logged at the end of the garbage collection task as Pending removals.

# proxmox-backup-client garbage-collect
starting garbage collection on store store2
Start GC phase1 (mark used chunks)
Start GC phase2 (sweep unused chunks)
percentage done: 1, chunk count: 219
percentage done: 2, chunk count: 453
...
percentage done: 99, chunk count: 21188
Removed bytes: 411368505
Removed chunks: 203
Original data bytes: 327160886391
Disk bytes: 52767414743 (16 %)
Disk chunks: 21221
Average chunk size: 2486565
TASK OK

Garbage collection can also be scheduled using proxmox-backup-manager or from the Proxmox Backup Server's web interface.

Benchmarking

The backup client also comes with a benchmarking tool. This tool measures various metrics relating to compression and encryption speeds. If a Proxmox Backup repository (remote or local) is specified, the TLS upload speed will get measured too.

You can run a benchmark using the benchmark subcommand of proxmox-backup-client:

Note

The TLS speed test is only included if a backup server repository is specified.

# proxmox-backup-client benchmark
Uploaded 1517 chunks in 5 seconds.
Time per request: 3309 microseconds.
TLS speed: 1267.41 MB/s
SHA256 speed: 2066.73 MB/s
Compression speed: 775.11 MB/s
Decompress speed: 1233.35 MB/s
AES256/GCM speed: 3688.27 MB/s
Verify speed: 783.43 MB/s
┌───────────────────────────────────┬─────────────────────┐
│ Name                              │ Value               │
╞═══════════════════════════════════╪═════════════════════╡
│ TLS (maximal backup upload speed) │ 1267.41 MB/s (103%) │
├───────────────────────────────────┼─────────────────────┤
│ SHA256 checksum computation speed │ 2066.73 MB/s (102%) │
├───────────────────────────────────┼─────────────────────┤
│ ZStd level 1 compression speed    │ 775.11 MB/s (103%)  │
├───────────────────────────────────┼─────────────────────┤
│ ZStd level 1 decompression speed  │ 1233.35 MB/s (103%) │
├───────────────────────────────────┼─────────────────────┤
│ Chunk verification speed          │ 783.43 MB/s (103%)  │
├───────────────────────────────────┼─────────────────────┤
│ AES256 GCM encryption speed       │ 3688.27 MB/s (101%) │
└───────────────────────────────────┴─────────────────────┘

Note

The percentages given in the output table correspond to a comparison against a Ryzen 7 2700X.

You can also pass the --output-format parameter to output stats in json, rather than the default table format.