[libvirt] Using Restore in another host.

Tue Apr 5 15:09:46 UTC 2011

Hi Marcela,
I was investigating the log file and it seems like the image file cannot
be opened on the remote host.

According to the lost you're doing the restore on the host named
rionegro so not the localhost. This seems like the saved guest image is
not accessible from the rionegro system. Could you please try to connect
to rionegro system using SSH and then connect to the default system
hypervisor using:

# virsh restore <image>

with no specification of remote system to connect to the default
hypervisor (default is qemu:///system under root account).

Also, what may be causing issues is the colon character (':') AFAIK so
try renaming the image from sv-chubut-2011-04-04-17:38 to some other
name without spaces and colon characters, e.g. to
sv-chubut-2011-04-04-17-38 and try to restore this way.

Since according to the code it's about opening file error I guess the
remote system is not having access to the file.

Michal

On 04/05/2011 04:54 PM, Marcela Castro León wrote:
> Hello
> This is the log I got doing the restore. It's says that it coun't get
> the image, but the image is ok, because I can startup the guest.
> Neither I can migrate the guest, so I suppose I've a problem in my
> configuration.
> Thank you very much in advance.
> Marcela.
>
> 2011/4/5 Michal Novotny <minovotn at redhat.com <mailto:minovotn at redhat.com>>
>
>     Hi Marcela,
>     is any other guest on the host that cannot restore this VM working
>     fine ?
>
>     You could also try running the:
>
>     */# LIBVIRT_DEBUG=1 virsh restore sv-chubut-2011-04-04-17:38 2>
>     virsh-restore.log
>
>     /*command which would enable the libvirt logging and output the debug
>     log into the virsh-restore.log file. This file could be sent to
>     the list
>     for analysis what's wrong.
>
>     Thanks,
>     Michal
>
>     On 04/05/2011 11:57 AM, Marcela Castro León wrote:
>     > Hello Daniel
>     > Thank you for all your information, but I still didn't solve the
>     > problem. I tried the option you mention, with two differents guest
>     > into two differents host, but all the cases I've got:
>     >
>     > */virsh # restore sv-chubut-2011-04-04-17:38/*
>     > */error: Failed to restore domain from sv-chubut-2011-04-04-17:38/*
>     > */error: monitor socket did not show up.: Connection refused/*
>     >
>     > I cannot get any useful information (at least form me) on the
>     log you
>     > mention.
>     > I'd appreciate a lot a new suggestion.
>     > Thanks
>     > Marcela
>     >
>     >
>     >
>     >
>     > 2011/4/4 Daniel P. Berrange <berrange at redhat.com
>     <mailto:berrange at redhat.com>
>     > <mailto:berrange at redhat.com <mailto:berrange at redhat.com>>>
>     >
>     >     On Sun, Apr 03, 2011 at 10:43:45AM +0200, Marcela Castro
>     León wrote:
>     >     > Hello:
>     >     > I need to know if I can use the restore operation (virsh o the
>     >     equivalent in
>     >     > libvirt) to recover a previous state of a guest, but recovered
>     >     previously in
>     >     > another host.
>     >     > I did a test, but I got an error:
>     >     >
>     >     > The exactly sequence using virsh I testes is:
>     >     > On [HOST SOURCE]: Using virsh
>     >     > 1) save [domain] [file]
>     >     > 2) restore file
>     >     > 3) destroy [domain]
>     >     >
>     >     > On [HOST SOURCE] using ubuntu sh
>     >     > 4) cp [guest.img] [guest.xml] [file] to HOST2
>     >     >
>     >     > On [HOST TARGET] using virsh
>     >     > 5) define [guest.xml] (using image on destination in HOST2)
>     >     > 6) restore [file]
>     >
>     >     As a general rule you should only ever 'restore' from a
>     >     file *once*. This is because after the first restore
>     >     operation, the guest may have made writes to its disk.
>     >     Restoring a second time the guest OS will likely have
>     >     an inconsistent view of the disk & will cause filesystem
>     >     corruption.
>     >
>     >     If you want to be able to restore from a saved image
>     >     multiple times, you need to also take a snapshot of
>     >     the disk image at the same time, and restore that
>     >     snapshot when restoring the memory image.
>     >
>     >
>     >     That aside, saving on one host & restoring on a
>     >     different host is fine. So if you leave out steps
>     >     2+3 in your example above, then your data would
>     >     still be safe.
>     >
>     >     > The restore troughs the following message:
>     >     > *virsh # restore sv-chubut-2011-04-01-09:58
>     >     > error: Failed to restore domain from
>     sv-chubut-2011-04-01-09:58
>     >     > error: monitor socket did not show up.: Connection refused*
>     >
>     >     There is probably some configuration difference on your 2nd host
>     >     that prevented the VM from starting up. If you're lucky the file
>     >     /var/log/libvirt/qemu/$NAME.log will tell you more
>     >
>     >     Daniel
>     >     --
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>     --
>     Michal Novotny <minovotn at redhat.com <mailto:minovotn at redhat.com>>,
>     RHCE
>     Virtualization Team (xen userspace), Red Hat
>
>

-- 
Michal Novotny <minovotn at redhat.com>, RHCE
Virtualization Team (xen userspace), Red Hat