btrfs-progs/Documentation/btrfs-send.asciidoc

btrfs-send(8)
=============

NAME
----
btrfs-send - generate a stream of changes between two subvolume snapshots

SYNOPSIS
--------
*btrfs send* [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]

DESCRIPTION
-----------

This command will generate a stream of instructions that describe changes
between two subvolume snapshots. The stream can be consumed by the *btrfs
receive* command to replicate the sent snapshot on a different filesystem.
The command operates in two modes: full and incremental.

All snapshots involved in one send command must be read-only, and this status
cannot be changed as long as there's a running send operation that uses the
snapshot.

In the full mode, the entire snapshot data and metadata will end up in the
stream.

In the incremental mode (options '-p' and '-c'), previously sent snapshots that
are available on both the sending and receiving side can be used to reduce the
amount of information that has to be sent to reconstruct the sent snapshot on a
different filesystem.

It is allowed to omit the '-p <parent>' option when '-c <clone-src>' options
are given, in which case *btrfs send* will determine a suitable parent among the
clone sources itself.

You must not specify clone sources unless you guarantee that these snapshots
are exactly in the same state on both sides, the sender and the receiver.

`Options`

-e::
if sending multiple subvolumes at once, use the new format and omit the
'end cmd' marker in the stream separating the subvolumes
-p <parent>::
send an incremental stream from 'parent' to 'subvol'
-c <clone-src>::
use this snapshot as a clone source for an incremental send (multiple allowed)
-f <outfile>::
output is normally written to standard output so it can be, for example, piped
to btrfs receive. Use this option to write it to a file instead.
--no-data::
send in 'NO_FILE_DATA' mode
+
The output stream does not contain any file
data and thus cannot be used to transfer changes. This mode is faster and
useful to show the differences in metadata.

-v|--verbose::
enable verbose output, print generated commands in a readable form, (each
occurrence of this option increases the verbosity level)
-q|--quiet::
suppress all messages except errors

EXIT STATUS
-----------
*btrfs send* returns a zero exit status if it succeeds. Non zero is
returned in case of failure.

AVAILABILITY
------------
*btrfs* is part of btrfs-progs.
Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
further details.

SEE ALSO
--------
`mkfs.btrfs`(8),
`btrfs-receive`(8)