borg create¶

Description¶

This command creates a backup archive containing all files found while recursively traversing all paths specified. Paths are added to the archive as they are given, that means if relative paths are desired, the command has to be run from the correct directory.

The slashdot hack in paths (recursion roots) is triggered by using /./: /this/gets/stripped/./this/gets/archived means to process that fs object, but strip the prefix on the left side of ./ from the archived items (in this case, this/gets/archived will be the path in the archived item).

When giving ‘-’ as path, borg will read data from standard input and create a file ‘stdin’ in the created archive from that data. In some cases it’s more appropriate to use --content-from-command, however. See section Reading from stdin below for details.

The archive will consume almost no disk space for files or parts of files that have already been stored in other archives.

The archive name needs to be unique. It must not end in ‘.checkpoint’ or ‘.checkpoint.N’ (with N being a number), because these names are used for checkpoints and treated in special ways.

In the archive name, you may use the following placeholders: {now}, {utcnow}, {fqdn}, {hostname}, {user} and some others.

Backup speed is increased by not reprocessing files that are already part of existing archives and weren’t modified. The detection of unmodified files is done by comparing multiple file metadata values with previous values kept in the files cache.

This comparison can operate in different modes as given by --files-cache:

• ctime,size,inode (default)

• mtime,size,inode (default behaviour of borg versions older than 1.1.0rc4)

• ctime,size (ignore the inode number)

• mtime,size (ignore the inode number)

• rechunk,ctime (all files are considered modified - rechunk, cache ctime)

• rechunk,mtime (all files are considered modified - rechunk, cache mtime)

• disabled (disable the files cache, all files considered modified - rechunk)

inode number: better safety, but often unstable on network filesystems

Normally, detecting file modifications will take inode information into consideration to improve the reliability of file change detection. This is problematic for files located on sshfs and similar network file systems which do not provide stable inode numbers, such files will always be considered modified. You can use modes without inode in this case to improve performance, but reliability of change detection might be reduced.

ctime vs. mtime: safety vs. speed

• ctime is a rather safe way to detect changes to a file (metadata and contents) as it can not be set from userspace. But, a metadata-only change will already update the ctime, so there might be some unnecessary chunking/hashing even without content changes. Some filesystems do not support ctime (change time). E.g. doing a chown or chmod to a file will change its ctime.

• mtime usually works and only updates if file contents were changed. But mtime can be arbitrarily set from userspace, e.g. to set mtime back to the same value it had before a content change happened. This can be used maliciously as well as well-meant, but in both cases mtime based cache modes can be problematic.

The mount points of filesystems or filesystem snapshots should be the same for every creation of a new archive to ensure fast operation. This is because the file cache that is used to determine changed files quickly uses absolute filenames. If this is not possible, consider creating a bind mount to a stable location.

The --progress option shows (from left to right) Original, Compressed and Deduplicated (O, C and D, respectively), then the Number of files (N) processed so far, followed by the currently processed path.

When using --stats, you will get some statistics about how much data was added - the “This Archive” deduplicated size there is most interesting as that is how much your repository will grow. Please note that the “All archives” stats refer to the state after creation. Also, the --stats and --dry-run options are mutually exclusive because the data is not actually compressed and deduplicated during a dry run.

For more help on include/exclude patterns, see the borg help patterns command output.

For more help on placeholders, see the borg help placeholders command output.

The --exclude patterns are not like tar. In tar --exclude .bundler/gems will exclude foo/.bundler/gems. In borg it will not, you need to use --exclude ‘*/.bundler/gems’ to get the same effect.

In addition to using --exclude patterns, it is possible to use --exclude-if-present to specify the name of a filesystem object (e.g. a file or folder name) which, when contained within another folder, will prevent the containing folder from being backed up. By default, the containing folder and all of its contents will be omitted from the backup. If, however, you wish to only include the objects specified by --exclude-if-present in your backup, and not include any other contents of the containing folder, this can be enabled through using the --keep-exclude-tags option.

The -x or --one-file-system option excludes directories, that are mountpoints (and everything in them). It detects mountpoints by comparing the device number from the output of stat() of the directory and its parent directory. Specifically, it excludes directories for which stat() reports a device number different from the device number of their parent. In general: be aware that there are directories with device number different from their parent, which the kernel does not consider a mountpoint and also the other way around. Linux examples for this are bind mounts (possibly same device number, but always a mountpoint) and ALL subvolumes of a btrfs (different device number from parent but not necessarily a mountpoint). macOS examples are the apfs mounts of a typical macOS installation. Therefore, when using --one-file-system, you should double-check that the backup works as intended.

backup-vm --id myvm --stdout | borg create REPO::ARCHIVE -

borg create --content-from-command REPO::ARCHIVE -- backup-vm --id myvm --stdout

Examples¶

# Backup ~/Documents into an archive named "my-documents"
$ borg create /path/to/repo::my-documents ~/Documents

# same, but list all files as we process them
$ borg create --list /path/to/repo::my-documents ~/Documents

# Backup /mnt/disk/docs, but strip path prefix using the slashdot hack
$ borg create /path/to/repo::docs /mnt/disk/./docs

# Backup ~/Documents and ~/src but exclude pyc files
$ borg create /path/to/repo::my-files \
    ~/Documents                       \
    ~/src                             \
    --exclude '*.pyc'

# Backup home directories excluding image thumbnails (i.e. only
# /home/<one directory>/.thumbnails is excluded, not /home/*/*/.thumbnails etc.)
$ borg create /path/to/repo::my-files /home \
    --exclude 'sh:home/*/.thumbnails'

# Backup the root filesystem into an archive named "root-YYYY-MM-DD"
# use zlib compression (good, but slow) - default is lz4 (fast, low compression ratio)
$ borg create -C zlib,6 --one-file-system /path/to/repo::root-{now:%Y-%m-%d} /

# Backup onto a remote host ("push" style) via ssh to port 2222,
# logging in as user "borg" and storing into /path/to/repo
$ borg create ssh://borg@backup.example.org:2222/path/to/repo::{fqdn}-root-{now} /

# Backup a remote host locally ("pull" style) using sshfs
$ mkdir sshfs-mount
$ sshfs root@example.com:/ sshfs-mount
$ cd sshfs-mount
$ borg create /path/to/repo::example.com-root-{now:%Y-%m-%d} .
$ cd ..
$ fusermount -u sshfs-mount

# Make a big effort in fine granular deduplication (big chunk management
# overhead, needs a lot of RAM and disk space, see formula in internals
# docs - same parameters as borg < 1.0 or attic):
$ borg create --chunker-params buzhash,10,23,16,4095 /path/to/repo::small /smallstuff

# Backup a raw device (must not be active/in use/mounted at that time)
$ borg create --read-special --chunker-params fixed,4194304 /path/to/repo::my-sdx /dev/sdX

# Backup a sparse disk image (must not be active/in use/mounted at that time)
$ borg create --sparse --chunker-params fixed,4194304 /path/to/repo::my-disk my-disk.raw

# No compression (none)
$ borg create --compression none /path/to/repo::arch ~

# Super fast, low compression (lz4, default)
$ borg create /path/to/repo::arch ~

# Less fast, higher compression (zlib, N = 0..9)
$ borg create --compression zlib,N /path/to/repo::arch ~

# Even slower, even higher compression (lzma, N = 0..9)
$ borg create --compression lzma,N /path/to/repo::arch ~

# Only compress compressible data with lzma,N (N = 0..9)
$ borg create --compression auto,lzma,N /path/to/repo::arch ~

# Use short hostname, user name and current time in archive name
$ borg create /path/to/repo::{hostname}-{user}-{now} ~
# Similar, use the same datetime format that is default as of borg 1.1
$ borg create /path/to/repo::{hostname}-{user}-{now:%Y-%m-%dT%H:%M:%S} ~
# As above, but add nanoseconds
$ borg create /path/to/repo::{hostname}-{user}-{now:%Y-%m-%dT%H:%M:%S.%f} ~

# Backing up relative paths by moving into the correct directory first
$ cd /home/user/Documents
# The root directory of the archive will be "projectA"
$ borg create /path/to/repo::daily-projectA-{now:%Y-%m-%d} projectA

# Use external command to determine files to archive
# Use --paths-from-stdin with find to only backup files less than 1MB in size
$ find ~ -size -1000k | borg create --paths-from-stdin /path/to/repo::small-files-only
# Use --paths-from-command with find to only backup files from a given user
$ borg create --paths-from-command /path/to/repo::joes-files -- find /srv/samba/shared -user joe
# Use --paths-from-stdin with --paths-delimiter (for example, for filenames with newlines in them)
$ find ~ -size -1000k -print0 | borg create \
    --paths-from-stdin \
    --paths-delimiter "\0" \
    /path/to/repo::smallfiles-handle-newline