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Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm
From: |
Wenchao Xia |
Subject: |
Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm |
Date: |
Wed, 12 Dec 2012 10:16:06 +0800 |
User-agent: |
Mozilla/5.0 (Windows NT 5.1; rv:16.0) Gecko/20121026 Thunderbird/16.0.2 |
OK, I'll adjust the code into the upstream framework, thanks for your
declaration.
> OK, I will try to give a short overview on the functionality.
>
> First, we decided to use 'internal' snapshots for our 'live snapshot'
> implementation.
> Internal snapshots almost always use some kind of reference counting, making
> snapshot action (like 'create/delete snapshot') quite efficient and fast.
>
> Internal snapshot totally depends on the storage backend. For now we can
> create
> internal snapshots on the following storage backend:
>
> * qcow2 files
> * rbd
> * sheepdog
> * nexenta iscsi
>
> As you can see, creating internal snapshots sometimes needs external tool.
> For example we use the
> nexenta API to create snapshots, while we use libiscsi to access them inside
> qemu.
>
> So our snapshot implementation uses the following steps:
>
> 1.) qmp: savevm-start [statefile]
>
> This save the VM state into [statefile] and then stops the VM.
>
> 2.) qga freezefs
>
> 3.) create snapshots: either using external tools or by qmp: snapshot-drive
>
> 4.) gqa unfreezefs
>
> 5.) qmp: savevm-end
>
> This restarts/resumes the VM
>
>> Have some questions:
>> in qmp_savevm_start(), vm_stop(RUN_STATE_SAVE_VM), I think this will
>> stop the VM running make it not lively, am I right?
>
> Yes, we need to halt the VM for a short period of time while we make
> snapshots. But that time is usually short.
>
> - Dietmar
>
--
Best Regards
Wenchao Xia
- [Qemu-devel] [RFC PATCH 0/2] live backup vm, Wenchao Xia, 2012/12/07
- [Qemu-devel] [RFC PATCH 1/2] live backup vm, export functions, Wenchao Xia, 2012/12/07
- [Qemu-devel] [RFC PATCH 2/2] live backup vm, snapshots all lively, Wenchao Xia, 2012/12/07
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/07
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Wenchao Xia, 2012/12/08
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/09
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Wenchao Xia, 2012/12/09
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/10
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Wenchao Xia, 2012/12/11
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/11
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm,
Wenchao Xia <=
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Paolo Bonzini, 2012/12/12
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/12
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Dietmar Maurer, 2012/12/12
- Re: [Qemu-devel] [RFC PATCH 0/2] live backup vm, Paolo Bonzini, 2012/12/12