btrfs-send man page
btrfs-send — generate a stream of changes between two subvolumes
btrfs send [-ve] [-p <parent>] [-c <clone-src>] [-f <outfile>] <subvol> [<subvol>...]
This command will generate a stream of instructions that describe changes between two subvolumes. The stream can be consumed by the btrfs receive command to replicate the sent subvolume on a different filesystem. The command operates in two modes: full and incremental.
All subvolumes involved in one send command must be read-only (ie. the read-only snapshots and this status cannot be changed if there’s a running send operation that uses the subvolume).
In the full mode, the entire subvolume data and metadata will end up in the stream.
In the incremental mode (options -p and -c), there can be one or more parent subvolumes that will establish the base for determining the changes. The final stream will be smaller compared to the full mode.
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.
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.
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.
enable verbose output, print generated commands in a readable form, (each occurrence of this option increases the verbosity level)
suppress all messages except errors
btrfs send returns a zero exit status if it succeeds. Non zero is returned in case of failure.
btrfs is part of btrfs-progs. Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for further details.