119 lines
4.0 KiB
ReStructuredText
119 lines
4.0 KiB
ReStructuredText
btrfs-send(8)
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=============
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SYNOPSIS
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--------
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**btrfs send** [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]
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DESCRIPTION
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-----------
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This command will generate a stream of instructions that describe changes
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between two subvolume snapshots. The stream can be consumed by the **btrfs
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receive** command to replicate the sent snapshot on a different filesystem.
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The command operates in two modes: full and incremental.
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All snapshots involved in one send command must be read-only, and this status
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cannot be changed as long as there's a running send operation that uses the
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snapshot. Read-only mount of the subvolume is not sufficient, there's no way to
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guarantee that there won't be any other writable mount of the same subvolume
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that would potentially write while send would be running.
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In the full mode, the entire snapshot data and metadata will end up in the
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stream.
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In the incremental mode (options *-p* and *-c*), previously sent snapshots that
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are available on both the sending and receiving side can be used to reduce the
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amount of information that has to be sent to reconstruct the sent snapshot on a
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different filesystem.
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The *-p <parent>* option can be omitted when *-c <clone-src>* options are
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given, in which case **btrfs send** will determine a suitable parent from among
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the clone sources.
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You must not specify clone sources unless you guarantee that these snapshots
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are exactly in the same state on both sides--both for the sender and the
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receiver. For implications of changed read-write status of a received snapshot
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please see section *SUBVOLUME FLAGS* in :doc:`btrfs-subvolume(8)<btrfs-subvolume>`.
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``Options``
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-e
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if sending multiple subvolumes at once, use the new format and omit the
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'end cmd' marker in the stream separating the subvolumes
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-p <parent>
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send an incremental stream from *parent* to *subvol*
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-c <clone-src>
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use this snapshot as a clone source for an incremental send (multiple
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allowed)
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-f <outfile>
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output is normally written to standard output so it can be, for
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example, piped to btrfs receive. Use this option to write it to a file
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instead.
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--no-data
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send in *NO_FILE_DATA* mode
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The output stream does not contain any file data and thus cannot be
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used to transfer changes. This mode is faster and is useful to show the
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differences in metadata.
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--proto <N>
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use send protocol version N
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The default is 1, which was the original protocol version. Version 2
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encodes file data slightly more efficiently; it is also required for
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sending compressed data directly (see *--compressed-data*). Version 2
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requires at least btrfs-progs 6.0 on both the sender and receiver and
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at least Linux 6.0 on the sender. Passing 0 means to use the highest
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version supported by the running kernel.
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--compressed-data
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send data that is compressed on the filesystem directly without
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decompressing it
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If the receiver supports the *BTRFS_IOC_ENCODED_WRITE* ioctl (added in
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Linux 6.0), it can also write it directly without decompressing it.
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Otherwise, the receiver will fall back to decompressing it and writing
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it normally.
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This requires protocol version 2 or higher. If *--proto* was not used,
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then *--compressed-data* implies *--proto 2*.
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-q|--quiet
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(deprecated) alias for global *-q* option
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-v|--verbose
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(deprecated) alias for global *-v* option
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``Global options``
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-q|--quiet
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suppress all messages except errors
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-v|--verbose
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increase output verbosity, print generated commands in a readable form
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EXIT STATUS
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-----------
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**btrfs send** returns a zero exit status if it succeeds. Non zero is
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returned in case of failure.
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AVAILABILITY
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------------
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**btrfs** is part of btrfs-progs. Please refer to the documentation at
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`https://btrfs.readthedocs.io <https://btrfs.readthedocs.io>`_.
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SEE ALSO
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--------
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:doc:`btrfs-receive(8)<btrfs-receive>`,
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:doc:`btrfs-subvolume(8)<btrfs-subvolume>`,
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:doc:`mkfs.btrfs(8)<mkfs.btrfs>`
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