ceph/doc/dev/rbd-diff.rst

RBD Incremental Backup
======================

This is a simple streaming file format for representing a diff between
two snapshots (or a snapshot and the head) of an RBD image.

Header
~~~~~~

"rbd diff v1\\n"

Metadata records
~~~~~~~~~~~~~~~~

Every record has a one byte "tag" that identifies the record type,
followed by some other data.

Metadata records come in the first part of the image.  Order is not
important, as long as all the metadata records come before the data
records.

From snap
---------

- u8: 'f'
- le32: snap name length
- snap name

To snap
-------

- u8: 't'
- le32: snap name length
- snap name

Size
----

- u8: 's'
- le64: (ending) image size

Data Records
~~~~~~~~~~~~

These records come in the second part of the sequence.

Updated data
------------

- u8: 'w'
- le64: offset
- le64: length
- length bytes of actual data

Zero data
---------

- u8: 'z'
- le64: offset
- le64: length


Final Record
~~~~~~~~~~~~

End
---

- u8: 'e'
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00			`RBD Incremental Backup`
			`======================`

			`This is a simple streaming file format for representing a diff between`
			`two snapshots (or a snapshot and the head) of an RBD image.`

			`Header`
doc/dev/rbd-diff: specify that metadata records come before data Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-29 04:19:32 +00:00			`~~~~~~`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
Fix formatting of header The header was displaying the newline as a simple "n" due to quoting in the doc. Signed-off-by: Christian Theune <ct@gocept.com> 2014-04-24 07:42:35 +00:00			`"rbd diff v1\\n"`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
doc/dev/rbd-diff: specify that metadata records come before data Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-29 04:19:32 +00:00			`Metadata records`
			`~~~~~~~~~~~~~~~~`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
doc/dev/rbd-diff: specify that metadata records come before data Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-29 04:19:32 +00:00			`Every record has a one byte "tag" that identifies the record type,`
			`followed by some other data.`

			`Metadata records come in the first part of the image. Order is not`
			`important, as long as all the metadata records come before the data`
			`records.`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
			`From snap`
			`---------`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 'f'`
			`- le32: snap name length`
			`- snap name`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
			`To snap`
			`-------`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 't'`
			`- le32: snap name length`
			`- snap name`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
			`Size`
			`----`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 's'`
dev/rbd-diff: clarify encoding of image size Fixes: #11562 Signed-off-by: Jason Dillaman <dillaman@redhat.com> 2015-05-22 15:18:09 +00:00			`- le64: (ending) image size`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
doc/dev/rbd-diff: specify that metadata records come before data Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-29 04:19:32 +00:00			`Data Records`
			`~~~~~~~~~~~~`

			`These records come in the second part of the sequence.`

rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00			`Updated data`
			`------------`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 'w'`
			`- le64: offset`
			`- le64: length`
			`- length bytes of actual data`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
			`Zero data`
			`---------`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 'z'`
			`- le64: offset`
			`- le64: length`
rbd: implement 'export-diff' and 'import-diff' commands Export a diff of an image from a previous snapshot to a file (or stdout). Import a diff and apply it to an image, and then create the ending snapshot. Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-26 20:32:28 +00:00
doc/dev/rbd-diff: specify that metadata records come before data Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-29 04:19:32 +00:00
			`Final Record`
			`~~~~~~~~~~~~`

doc/dev/rbd-diff: update incremental file format Signed-off-by: Sage Weil <sage@inktank.com> 2013-03-28 21:19:59 +00:00			`End`
			`---`

dev/rbd-diff: make formats into bullet lists (solves linebreak probs) Signed-off-by: Dan Mick <dan.mick@inktank.com> 2013-06-05 00:23:52 +00:00			`- u8: 'e'`