Re: [Qemu-devel] [PATCH v2 0/6] Mirrored writes using blockdev-transaction

[Anthony Liguori]

On 03/01/2012 05:21 AM, Paolo Bonzini wrote:
> This implements all ingredients to establish mirrored writes.
> The drive-reopen command that is used to terminate mirrored writes
> is not included in this series.
>
> Tested with the following scenarios:
>
> a) mirror only
>
> 1) create base.qcow2 and start QEMU with it
>
> 2) Execute the following QMP command
>
> { "execute": "qmp_capabilities" }
> { "execute": "blockdev-transaction", "arguments":
>    {'actions': [
>      { 'type': 'mirror', 'data' :
>        { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } }
> { "execute": "cont" }
>
> 3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock)
>
> 4) restart the guest with mirror.qcow2
>
>
> b) atomic snapshot+mirror
>
> 1) start QEMU with an existing image test.img
>
> 2) Execute the following QMP command
>
> { "execute": "qmp_capabilities" }
> { "execute": "blockdev-transaction", "arguments":
>    {'actions': [
>      { 'type': 'snapshot', 'data' :
>        { 'device': 'ide0-hd0', 'snapshot-file': '/home/pbonzini/base.qcow2' } },
>      { 'type': 'mirror', 'data' :
>        { 'device': 'ide0-hd0', 'target': '/home/pbonzini/mirror.qcow2' } } ] } }
> { "execute": "cont" }

We don't have schema introspection today.  How would one determine when new 
transaction types are available?

I think we need some sort of introspection method too in order for clients to 
figure out when the command is extended.

Regards,

Anthony Liguori

> 3) hibernate the guest (this requires an IDE disk and -cpu kvm64,-kvmclock)
>
> 4) check that mirror.qcow2 has test.img as the base
>
> 5) restart the guest with base.qcow2
>
> 6) restart the guest with mirror.qcow2
>
> v1->v2:
>         Removed wrong assertions in patches 3 and 6
>         Move new_image_file and other variables inside the while loop (Federico)
>         Rename new_source_file to new_source (Federico)
>         Fix image name in error message (Federico)
>         Fixed documentation in qapi-schema.json (Federico)
>         Fixed documentation and example in qmp-commands.hx (Eric)
>         Added back AIO (Stefan), with fixes to cancellation
>
>
> Marcelo Tosatti (1):
>    Add blkmirror block driver
>
> Paolo Bonzini (5):
>    fix format name for backing file
>    qapi: complete implementation of unions
>    rename blockdev-group-snapshot-sync
>    add reuse field
>    add mirroring to blockdev-transaction
>
>   Makefile.objs             |    2 +-
>   block/blkmirror.c         |  239 +++++++++++++++++++++++++++++++++++++++++++++
>   blockdev.c                |  114 ++++++++++++++--------
>   qapi-schema-test.json     |   10 ++
>   qapi-schema.json          |   51 ++++++++--
>   qmp-commands.hx           |   68 +++++++++----
>   scripts/qapi-types.py     |    5 +
>   scripts/qapi-visit.py     |   31 ++++++-
>   test-qmp-input-visitor.c  |   18 ++++
>   test-qmp-output-visitor.c |   34 +++++++
>   10 files changed, 496 insertions(+), 76 deletions(-)
>   create mode 100644 block/blkmirror.c