Re: [Qemu-devel] [PATCH 0/3 v5] Live migration without shared storage

[Avi Kivity]

On 11/03/2009 11:40 AM, Liran Schour wrote:
> - Liran
>
> Avi Kivity<address@hidden>  wrote on 02/11/2009 20:47:34:
>    
> > On 11/02/2009 03:40 PM, address@hidden wrote:
> >      
> > > This series adds support for live migration without shared storage,
> > >        
> means
>    
> > > copy the storage while migrating. It was tested with KVM. Supports 2
> > >        
> ways
>    
> > > to replicate the storage during migration:
> > > 1. Complete copy of storage to destination
> > > 2. Assuming the storage is cow based, copy only the allocated
> > > data, time of the migration will be linear with the amount of allocated
> > > data (user responsibility to verify that the same backend file reside
> > > on src and destination).
> > >
> > > Live migration will work as follows:
> > > (qemu) migrate -d tcp:0:4444 # for ordinary live migration
> > > (qemu) migrate -d blk tcp:0:4444 # for live migration with
> > >        
> > complete storage copy
> >      
> > > (qemu) migrate -d blk inc tcp:0:4444 # for live migration with
> > >        
> > incremental storage copy, storage is cow based.
> >      
> > >        
> > I'd like to see the syntax generalized.  For one, the guest may have
> > several disks; an install image cdrom might be available as an nfs image
> > but the main storage is local.  Secondly, there can be several levels of
> > cow and we want to control which one we copy.
> >
> > I'll leave the exact details to the qpeople, but if we can specify a
> > copy depth for each device, where 0=copy nothing, n=copy everything,
> > 1=copy the last level (equivalent to -d blk inc) I think we'll have
> > covered everything.
> >      
> I propose the following syntax:
> migrate [-d] [-b [<device:copy_level>  ...<device:copy_level>]]
> tcp:<host>:<port>
> Where device will be the name of the device: ide0-hd0. And copy_level will
> be integer or n, 0=flat copy of the device, 1=copy the last level ...
> n=copy all levels.
> All HD devices that will not appear in the command will be treated as
> copy_level=0. All devices != BDRV_TYPE_HD will be ignored.
>
>    

Looks good.

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