Re: [Qemu-devel] [PATCH v2 0/6] external backup api

[Fam Zheng <famz@redhat.com>]

On Wed, 02/03 13:57, Vladimir Sementsov-Ogievskiy wrote:
> On 03.02.2016 11:14, Fam Zheng wrote:
> >On Sat, 01/30 13:56, Vladimir Sementsov-Ogievskiy wrote:
> >>Hi all.
> >>
> >>These series which aims to add external backup api. This is needed to allow
> >>backup software use our dirty bitmaps.
> >>
> >>Vmware and Parallels Cloud Server have this feature.
> >What is the advantage of this appraoch over "drive-backup sync=incremental
> >..."?
> 
> Hmm, you are asking about advantage of external backup over
> internal? It depends on external backup tool.

I'm asking why the tool can't use drive-backup to achieve what you want. They
seem very comparable.

Fam

> 
> >
> >>There are three things are done:
> >>- add query-block-dirty-bitmap-ranges qmp command
> >>- add qmp commands for dirty-bitmap functions: create_successor, abdicate,
> >>   reclaim.
> >>- make create-successor command transaction-able
> >>
> >>Then, external backup should be done like this:
> >>
> >>1.  qmp transaction {
> >>         external-snapshot
> >>         bitmap-create-successor
> >>     }
> >>
> >>2.  qmp query frozen bitmap, not acquiring aio context.
> >What do you do with the query response, read the snapshot image with an
> >external tool?
> 
> Yes. Alternatively, image fleecing may be used instead of snapshot.
> 
> >
> >Fam
> >
> >>3.  do external backup, using snapshot and bitmap
> >>
> >>
> >>4.  if (success backup)
> >>         qmp bitmap-abdicate
> >>     else
> >>         qmp bitmap-reclaime
> >>
> >>5.  qmp merge snapshot
> >>
> >>
> >>v2: a lot of additions and changes, no sense to compare with v1
> >>
> >>
> >>Vladimir Sementsov-Ogievskiy (6):
> >>   block dirty bitmap: add next_zero function
> >>   qmp: add query-block-dirty-bitmap-ranges
> >>   iotests: test query-block-dirty-bitmap-ranges
> >>   qapi: add qmp commands for some dirty bitmap functions
> >>   qapi: make block-dirty-bitmap-create-successor transaction-able
> >>   iotests: test external backup api
> >>
> >>  block/dirty-bitmap.c         |  60 ++++++++++++++++++++++
> >>  blockdev.c                   | 113 +++++++++++++++++++++++++++++++++++++++++
> >>  include/block/dirty-bitmap.h |   9 ++++
> >>  include/qemu/hbitmap.h       |   8 +++
> >>  qapi-schema.json             |   4 +-
> >>  qapi/block-core.json         |  90 +++++++++++++++++++++++++++++++++
> >>  qmp-commands.hx              | 118 +++++++++++++++++++++++++++++++++++++++++++
> >>  tests/qemu-iotests/150       |  88 ++++++++++++++++++++++++++++++++
> >>  tests/qemu-iotests/150.out   |  21 ++++++++
> >>  tests/qemu-iotests/151       |  77 ++++++++++++++++++++++++++++
> >>  tests/qemu-iotests/151.out   |   7 +++
> >>  tests/qemu-iotests/group     |   2 +
> >>  util/hbitmap.c               |  26 ++++++++++
> >>  13 files changed, 622 insertions(+), 1 deletion(-)
> >>  create mode 100755 tests/qemu-iotests/150
> >>  create mode 100644 tests/qemu-iotests/150.out
> >>  create mode 100755 tests/qemu-iotests/151
> >>  create mode 100644 tests/qemu-iotests/151.out
> >>
> >>-- 
> >>1.8.3.1
> >>
> 
> 
> -- 
> Best regards,
> Vladimir
>