Re: [Xen-users] Xen Migration Trouble

[Joe <jnirsch@xxxxxxxxxxx>]

Hey,

I've continued to look into it but am getting stuck.
My ultimate goal is to get live migration working.  My confusing comes 
in how to get live migration working.  I have looked at several sources 
and followed their steps which were all similar (one of which is: 
http://iquaid.org/DevFu/files/xen-live-migration.pdf).  However, I am having am issues with migration (offline and live).
I followed the set up of the above PDF.

1) The error I am confused about is: "error: POST operation failed: xend_post: error from xen daemon: No such domain test?"

I am able to do xm create and xm destroy just fine.  xm shutdown and xm reboot don't do anything for my domain.
With xm save, a 1008 byte file is created but xm restore fails (on same host).  Which I find odd.

>From GUI:
Unable to migrate guest:
 Traceback (most recent call last):




  File "/usr/share/virt-manager/virtManager/migrate.py", line 449, in _async_migrate
    vm.migrate(dstconn, migrate_uri, rate, live, secure)
  File "/usr/share/virt-manager/virtManager/domain.py", line 1388, in migrate




    self.vm.migrate(destconn.vmm, flags, newname, interface, rate)
  File "/usr/lib/python2.4/site-packages/libvirt.py", line 378, in migrate
    if ret is None:raise libvirtError('virDomainMigrate() failed', dom=self)




libvirtError: POST operation failed: xend_post: error from xen daemon: No such domain test

>From console:
# /usr/sbin/xm migrate test xen+ssh://domain.com
Error: Domain 'test' does not exist.


# virsh migrate test xen+ssh://domain.com
error: POST operation failed: xend_post: error from xen daemon: No such domain test

I have looked for the source, but it issue appears to be with virDomainMigrate(), in a compiled binary libvirtmod.so, so I cannot determine where it is looking for the files.

2) Most recently, another issue I am having is a high memory usage by 
Dom0.  I am not sure why this is occurring.  Nothing I have done with 
trying to live migrate should cause the Dom0 to use all its allocated 
memory from boot (its constantly at 96% and is allocated 10 GB). What 
could be causing this bloat and how to fix it?

Thanks.

On Wed, Dec 22, 2010 at 10:14 AM, Todd Deshane <todd.deshane@xxxxxxx> wrote:

On Wed, Dec 22, 2010 at 11:03 AM, Joe <jnirsch@xxxxxxxxxxx> wrote:
> I am trying to perform offline and live migration with xen.
>
> I have two identical hosts, host1 and host2, which are both RHEL5.  I have
> an NFS server on host1.  The NFS location is not the root of the file
> system.  The domU I am trying to migrate is FC14 fully virtualized.  The
> host environments are set up exactly the same.  I have edited the
> xend-config.sxp to ensure that relocation is possible.
>
> Xen information:
> # virsh version
> Compiled against library: libvir 0.6.3
> Using library: libvir 0.6.3
> Using API: Xen 3.0.1
> Running hypervisor: Xen 3.1.0
>
> To perform these migrations, I am using using the virt-manager GUI.  I have
> tried CLI and had the same success.
> Initially, when I did both migration techniques, I got the following error
> message, where 'test' was the domU I was trying to migrate.
>
> Unable to migrate guest:
>  Traceback (most recent call last):
>   File "/usr/share/virt-manager/virtManager/migrate.py", line 449, in
> _async_migrate
>     vm.migrate(dstconn, migrate_uri, rate, live, secure)
>   File "/usr/share/virt-manager/virtManager/domain.py", line 1388, in
> migrate
>     self.vm.migrate(destconn.vmm, flags, newname, interface, rate)
>   File "/usr/lib/python2.4/site-packages/libvirt.py", line 378, in migrate
>     if ret is None:raise libvirtError('virDomainMigrate() failed', dom=self)
> libvirtError: POST operation failed: xend_post: error from xen daemon: No
> such domain test
>
> Doing offline migration with CLI, I get:
> # virsh migrate test xen+ssh://domain.com
> error: failed to get domain 'test'
> error: Domain not found: xenUnifiedDomainLookupByName
>
> In the 'test' config file, I include nfs_root, root, and nfs_server.
>
> Now, I still get that error with offline migration.  When I am performing
> live migration, it freezes on a screen saying migration in progress.  When
> it freezes, the target host has the vm appear but lists it as no state (from
> virsh list).  On the source host, the target still exists and is switching
> between running and shutoff (virsh list lists it as idle).  I believe what
> is currently happening with the live migration is just a fluke.
>
> As far as I can tell, I have set up all the components right.  The firewall
> or selinux is not the issue.  User permissions are not an issue and have
> been addressed.  To sum up this long rant, here are a few questions.  What
> is xend_post?  What does "xen daemon: No such domain" mean?  I think it
> might be searching the wrong location, but cannot tell where that is.
> Should the vm config files be on each host in /etc/xen or in the NFS
> location?  Where can I enable more complete logging for xen and libvirt?
> Currently, unless the vm is running on one host, I do not see it in the GUI
> unless I created it using xm create to start a vm.  I find this odd but do
> not know how to correct it.
>
> Thanks for any help.

I would recommend using the xm commands directly to try to narrow down
the problem.

For example you can do xm save, copy the file and do xm restore on the
other host to see if that work.

Hope that helps.

Thanks,
Todd

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