[libvirt-users] A issue about KVM block migration

[Eric Blake]

On 01/13/2013 05:53 AM, 刘基  wrote:
> Hello everyone,
> 
> I have a issue about the KVM block migration. Please give me some help.
> 
> 1)  I use the "virsh create" command to start a KVM VM in source machine.
> 2) And then, I use "virsh migrate" cammand to start a block migration:
>    # virsh migrate --live --copy-storage-all --verbose win7 qemu+ssh://
> 186.100.8.136/system

The current implementation of --copy-storage-all uses a qemu interface
that upstream qemu developers are reluctant to support, and risks
running into problems.  We have patches under review to use a new NBD
server for migration when targeting qemu 1.4 with libvirt 1.0.2, with
much less risk, but that probably won't help your particular situation.

> 
> 3) But after a few minutes，there have a error:
>    # virsh migrate --live --copy-storage-all --verbose win7 qemu+ssh://
> 186.100.8.136/system
>    root at 186.100.8.136's password:
>    Migration : [ 97% ]
>    error: Unable to read from monitor : Connection reset by peer.

I don't know if this was a case of libvirt timing out; you may want to
play with keepalive_interval and keepalive_count in
/etc/libvirt/libvirtd.conf with longer or disabled timeouts, on both
source and destination, to see if that matters.  You might also want to
look into the libvirt logs to see if there are more details about the
failure.

> 
>    I execute "virsh list" command in source machine again, and the result
> is NULL.

That's not supposed to happen - a failed migration is supposed to leave
the guest running on the source.  But since it did happen, it would be
nice to get to a root cause, and see if there is a bug we need to fix.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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