[Qemu-devel] [RFC PATCH 00/14] Block replication for continuous checkpoints

[Wen Congyang]

Block replication is a very important feature which is used for
continuous checkpoints(for example: COLO).

Usage:
Primary:
  -drive if=xxx,driver=quorum,read-pattern=first,\
         children.0.file.filename=1.raw,\
         children.0.driver=raw,\
         children.1.file.driver=nbd+colo,\
         children.1.file.host=xxx,\
         children.1.file.port=xxx,\
         children.1.file.export=xxx,\
         children.1.driver=raw
  Note:
  1. NBD Client should not be the first child of quorum.
  2. There should be only one NBD Client.
  3. host is the secondary physical machine's hostname or IP
  4. Each disk must have its own export name.

Secondary:
  -drive if=xxx,driver=blkcolo,export=xxx,\
         backing.file.filename=1.raw,\
         backing.driver=raw
  Then run qmp command:
    nbd_server_start host:port
  Note:
  1. The export name for the same disk must be the same in primary
     and secondary QEMU command line
  2. The qmp command nbd_server_start must be run before running the
     qmp command migrate on primary QEMU
  3. Don't use nbd_server_start's other options

You can get the patch here:
https://github.com/wencongyang/qemu-colo/commits/block-replication-v1

Wen Congyang (14):
  docs: block replication's description
  quorom: add a new read pattern
  quorum: ignore 0-length child
  Add new block driver interfaces to control disk replication
  quorom: implement block driver interfaces for block replication
  NBD client: connect to nbd server later
  NBD client: implement block driver interfaces for block replication
  block: add a new API to create a hidden BlockBackend
  block: give backing image its own BlockBackend
  allow the backing image access the origin BlockDriverState
  allow writing to the backing file
  Add disk buffer for block replication
  COW: move cow interfaces to a seperate file
  COLO: implement a new block driver

 Makefile.objs                  |   2 +-
 block.c                        |  53 +++++-
 block/Makefile.objs            |   1 +
 block/backup.c                 |  52 +-----
 block/blkcolo-buffer.c         | 324 ++++++++++++++++++++++++++++++++
 block/blkcolo.c                | 409 +++++++++++++++++++++++++++++++++++++++++
 block/blkcolo.h                |  35 ++++
 block/block-backend.c          |  29 ++-
 block/nbd.c                    | 155 ++++++++++++++--
 block/quorum.c                 |  79 +++++++-
 blockcow.c                     |  52 ++++++
 docs/block-replication.txt     | 129 +++++++++++++
 include/block/block.h          |  27 +++
 include/block/block_int.h      |  14 ++
 include/sysemu/block-backend.h |   2 +
 qapi/block-core.json           |   4 +-
 16 files changed, 1295 insertions(+), 72 deletions(-)
 create mode 100644 block/blkcolo-buffer.c
 create mode 100644 block/blkcolo.c
 create mode 100644 block/blkcolo.h
 create mode 100644 blockcow.c
 create mode 100644 docs/block-replication.txt

-- 
2.1.0