mirror of
https://github.com/kdave/btrfs-progs
synced 2024-12-25 23:52:17 +00:00
24 lines
1.3 KiB
ReStructuredText
24 lines
1.3 KiB
ReStructuredText
Send/receive
|
|
============
|
|
|
|
Send and receive are complementary features that allow to transfer data from
|
|
one filesystem to another in a streamable format. The send part traverses a
|
|
given read-only subvolume and either creates a full stream representation of
|
|
its data and metadata (*full mode*), or given a set of subvolumes for reference
|
|
it generates a difference relative to that set (*incremental mode*).
|
|
|
|
Receive on the other hand takes the stream and reconstructs a subvolume with
|
|
files and directories equivalent to the filesystem that was used to produce the
|
|
stream. The result is not exactly 1:1, e.g. inode numbers can be different and
|
|
other unique identifiers can be different (like the subvolume UUIDs). The full
|
|
mode starts with an empty subvolume, creates all the files and then turns the
|
|
subvolume to read-only. At this point it could be used as a starting point for a
|
|
future incremental send stream, provided it would be generated from the same
|
|
source subvolume on the other filesystem.
|
|
|
|
The stream is a sequence of encoded commands that change e.g. file metadata
|
|
(owner, permissions, extended attributes), data extents (create, clone,
|
|
truncate), whole file operations (rename, delete). The stream can be sent over
|
|
network, piped directly to the receive command or saved to a file. Each command
|
|
in the stream is protected by a CRC32C checksum.
|