Block replication is a very important feature which is used for continuous checkpoints(for example: COLO).
You can get the detailed information about block replication from here: http://wiki.qemu.org/Features/BlockReplication Usage: Please refer to docs/block-replication.txt You can get the patch here: https://github.com/Pating/qemu/tree/changlox/block-replication-v20 You can get the patch with framework here: https://github.com/Pating/qemu/tree/changlox/colo_framework_v19 TODO: 1. Continuous block replication. It will be started after basic functions are accepted. Changs Log: V20: 1. Rebase to the lastest code 2. Address comments from stefan p8: 1. error_setg() with an error message when check_top_bs() fails. 2. remove bdrv_ref(s->hidden_disk->bs) since commit 5c438bc6 3. use bloc_job_cancel_sync() before active commit p9: 1. fix uninitialized 'pattern_buf' 2. introduce mkstemp(3) to fix unique filenames 3. use qemu_vfree() for qemu_blockalign() memory 4. add missing replication_start_all() 5. remove useless pattern for io_write() V19: 1. Rebase to v2.6.0 2. Address comments from stefan p3: a new patch that export interfaces for extra serialization p8: 1. call replication_stop() before freeing s->top_id 2. check top_bs 3. reopen file readonly in error return paths 4. enable extra serialization between read and COW p9: try to hanlde SIGABRT V18: p6: add local_err in all replication callbacks to prevent "errp == NULL" p7: add missing qemu_iovec_destroy(xxx) V17: 1. Rebase to the lastest codes p2: refactor backup_do_checkpoint addressed comments from Jeff Cody p4: fix bugs in "drive_add buddy xxx" hmp commands p6: add "since: 2.7" p7: fix bug in replication_close(), add missing "qapi/error.h", add test-replication p8: add "since: 2.7" V16: 1. Rebase to the newest codes 2. Address comments from Stefan & hailiang p3: we don't need this patch now p4: add "top-id" parameters for secondary p6: fix NULL pointer in replication callbacks, remove unnecessary typedefs, add doc comments that explain the semantics of Replication p7: Refactor AioContext for thread-safe, remove unnecessary get_top_bs() *Note*: I'm working on replication testcase now, will send out in V17 V15: 1. Rebase to the newest codes 2. Fix typos and coding style addresed Eric's comments 3. Address Stefan's comments 1) Make backup_do_checkpoint public, drop the changes on BlockJobDriver 2) Update the message and description for [PATCH 4/9] 3) Make replication_(start/stop/do_checkpoint)_all as global interfaces 4) Introduce AioContext lock to protect start/stop/do_checkpoint callbacks 5) Use BdrvChild instead of holding on to BlockDriverState * pointers 4. Clear BDRV_O_INACTIVE for hidden disk's open_flags since commit 09e0c771 5. Introduce replication_get_error_all to check replication status 6. Remove useless discard interface V14: 1. Implement auto complete active commit 2. Implement active commit block job for replication.c 3. Address the comments from Stefan, add replication-specific API and data structure, also remove old block layer APIs V13: 1. Rebase to the newest codes 2. Remove redundant marcos and semicolon in replication.c 3. Fix typos in block-replication.txt V12: 1. Rebase to the newest codes 2. Use backing reference to replcace 'allow-write-backing-file' V11: 1. Reopen the backing file when starting blcok replication if it is not opened in R/W mode 2. Unblock BLOCK_OP_TYPE_BACKUP_SOURCE and BLOCK_OP_TYPE_BACKUP_TARGET when opening backing file 3. Block the top BDS so there is only one block job for the top BDS and its backing chain. V10: 1. Use blockdev-remove-medium and blockdev-insert-medium to replace backing reference. 2. Address the comments from Eric Blake V9: 1. Update the error messages 2. Rebase to the newest qemu 3. Split child add/delete support. These patches are sent in another patchset. V8: 1. Address Alberto Garcia's comments V7: 1. Implement adding/removing quorum child. Remove the option non-connect. 2. Simplify the backing refrence option according to Stefan Hajnoczi's suggestion V6: 1. Rebase to the newest qemu. V5: 1. Address the comments from Gong Lei 2. Speed the failover up. The secondary vm can take over very quickly even if there are too many I/O requests. V4: 1. Introduce a new driver replication to avoid touch nbd and qcow2. V3: 1: use error_setg() instead of error_set() 2. Add a new block job API 3. Active disk, hidden disk and nbd target uses the same AioContext 4. Add a testcase to test new hbitmap API V2: 1. Redesign the secondary qemu(use image-fleecing) 2. Use Error objects to return error message 3. Address the comments from Max Reitz and Eric Blake Changlong Xie (3): Backup: export interfaces for extra serialization Introduce new APIs to do replication operation tests: add unit test case for replication Wen Congyang (7): unblock backup operations in backing file Backup: clear all bitmap when doing block checkpoint Link backup into block core docs: block replication's description auto complete active commit Implement new driver for block replication support replication driver in blockdev-add Makefile.objs | 1 + block.c | 17 ++ block/Makefile.objs | 3 +- block/backup.c | 59 +++- block/mirror.c | 13 +- block/replication.c | 657 +++++++++++++++++++++++++++++++++++++++++++ blockdev.c | 2 +- docs/block-replication.txt | 239 ++++++++++++++++ include/block/block_backup.h | 17 ++ include/block/block_int.h | 3 +- qapi/block-core.json | 33 ++- qemu-img.c | 2 +- replication.c | 105 +++++++ replication.h | 176 ++++++++++++ tests/.gitignore | 1 + tests/Makefile | 4 + tests/test-replication.c | 555 ++++++++++++++++++++++++++++++++++++ 17 files changed, 1870 insertions(+), 17 deletions(-) create mode 100644 block/replication.c create mode 100644 docs/block-replication.txt create mode 100644 include/block/block_backup.h create mode 100644 replication.c create mode 100644 replication.h create mode 100644 tests/test-replication.c -- 1.9.3
