Re: [Qemu-devel] segfault while booting from saved snapshot

Re: [Qemu-devel] segfault while booting from saved snapshot

[Shehbaz Jaffer]

Hi,

Could anyone please give me the command to do live-migration to to a
file? I have tried searching on QEMU Wiki but all the articles that I
have come across point to snapshotting the disk, and not the entire VM
to a file.

Appreciate your help.

Thanks,
Shehbaz

On Sat, Apr 19, 2014 at 11:07 PM, Shehbaz Jaffer
<shehbazjaffer007@gmail.com> wrote:
> Thankyou for your reply. Live migration does seem like an interesting option
> to explore. I will look into it and get back if I get stuck.
>
>
> On Wed, Apr 16, 2014 at 6:16 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>>
>> Am 15.04.2014 um 16:55 hat Shehbaz Jaffer geschrieben:
>> > Thankyou for your reply. I do not face the error using qemu.1.7.1
>> > version.
>> >
>> > 1 quick question:
>> >
>> > I want to create a qcow2 image file after my VM has completed booting;
>> > i.e.,
>> > when I boot from this new snapshot, I should directly get to my VMs
>> > login
>> > prompt. How can i create such a qcow2 snapshot?
>> >
>> > I tried stopped the VM using QMP after the VM had completed booting, and
>> > then
>> > using host CLI to create a qcow2 image :
>> >
>> > qemu-img create -b ubuntu.qcow2 -f qcow2 newsnap.qcow2
>> >
>> > This created a new qcow2 file - newsnap.qcow2 on top of ubuntu.qcow2,
>> > however
>> > when I boot using newsnap.qcow2, It takes me again through the complete
>> > boot
>> > process - till the login prompt.
>> >
>> > Is there a way to create the qcow2 snapshot after VM has completed
>> > booting?
>>
>> The reason for this is that you only create a snapshot of the disk this
>> way, not of the VM state (i.e. RAM contents, device states, etc.)
>>
>> The most convenient way when you're using qemu directly is probably
>> using internal snapshots. This is what the savevm/loadvm HMP commands
>> provide (not sure if there is a QMP equivalent); you can also use the
>> -loadvm command line parameter to start a VM from a snapshot.
>>
>> Another option is that you take an external snapshot in a new qcow2 file
>> like you did, but you additionally do a live migration into a file. When
>> restarting the VM, you need to use the -incoming option and feed that
>> file back to qemu. As this is a bit more cumbersome, this is probably
>> more an option for management tools than for manual use.
>>
>> Kevin
>
>
>
>
> --
> Shehbaz Jaffer
> MTS | Advanced Technology Group |  NetApp



-- 
Shehbaz Jaffer
MTS | Advanced Technology Group |  NetApp

Re: [Qemu-devel] segfault while booting from saved snapshot

[Kevin Wolf]

Am 13.05.2014 um 10:20 hat Shehbaz Jaffer geschrieben:
> Hi,
> 
> Could anyone please give me the command to do live-migration to to a
> file? I have tried searching on QEMU Wiki but all the articles that I
> have come across point to snapshotting the disk, and not the entire VM
> to a file.

In the HMP monitor: migrate "exec:cat > /tmp/vmstate"

Kevin

> Appreciate your help.
> 
> Thanks,
> Shehbaz
> 
> On Sat, Apr 19, 2014 at 11:07 PM, Shehbaz Jaffer
> <shehbazjaffer007@gmail.com> wrote:
> > Thankyou for your reply. Live migration does seem like an interesting option
> > to explore. I will look into it and get back if I get stuck.
> >
> >
> > On Wed, Apr 16, 2014 at 6:16 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> >>
> >> Am 15.04.2014 um 16:55 hat Shehbaz Jaffer geschrieben:
> >> > Thankyou for your reply. I do not face the error using qemu.1.7.1
> >> > version.
> >> >
> >> > 1 quick question:
> >> >
> >> > I want to create a qcow2 image file after my VM has completed booting;
> >> > i.e.,
> >> > when I boot from this new snapshot, I should directly get to my VMs
> >> > login
> >> > prompt. How can i create such a qcow2 snapshot?
> >> >
> >> > I tried stopped the VM using QMP after the VM had completed booting, and
> >> > then
> >> > using host CLI to create a qcow2 image :
> >> >
> >> > qemu-img create -b ubuntu.qcow2 -f qcow2 newsnap.qcow2
> >> >
> >> > This created a new qcow2 file - newsnap.qcow2 on top of ubuntu.qcow2,
> >> > however
> >> > when I boot using newsnap.qcow2, It takes me again through the complete
> >> > boot
> >> > process - till the login prompt.
> >> >
> >> > Is there a way to create the qcow2 snapshot after VM has completed
> >> > booting?
> >>
> >> The reason for this is that you only create a snapshot of the disk this
> >> way, not of the VM state (i.e. RAM contents, device states, etc.)
> >>
> >> The most convenient way when you're using qemu directly is probably
> >> using internal snapshots. This is what the savevm/loadvm HMP commands
> >> provide (not sure if there is a QMP equivalent); you can also use the
> >> -loadvm command line parameter to start a VM from a snapshot.
> >>
> >> Another option is that you take an external snapshot in a new qcow2 file
> >> like you did, but you additionally do a live migration into a file. When
> >> restarting the VM, you need to use the -incoming option and feed that
> >> file back to qemu. As this is a bit more cumbersome, this is probably
> >> more an option for management tools than for manual use.
> >>
> >> Kevin
> >
> >
> >
> >
> > --
> > Shehbaz Jaffer
> > MTS | Advanced Technology Group |  NetApp
> 
> 
> 
> -- 
> Shehbaz Jaffer
> MTS | Advanced Technology Group |  NetApp

Re: [Qemu-devel] segfault while booting from saved snapshot

[Shehbaz Jaffer]

On Tue, May 13, 2014 at 2:08 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 13.05.2014 um 10:20 hat Shehbaz Jaffer geschrieben:
>> Hi,
>>
>> Could anyone please give me the command to do live-migration to to a
>> file? I have tried searching on QEMU Wiki but all the articles that I
>> have come across point to snapshotting the disk, and not the entire VM
>> to a file.
>
> In the HMP monitor: migrate "exec:cat > /tmp/vmstate"
>
Thanks, It worked.

For others who want to do the same please note:
We can load the vmstate saved earlier appending:

-incoming "exec:cat /tmp/vmstate"

to the command while launching the new VM.

> Kevin
>
>> Appreciate your help.
>>
>> Thanks,
>> Shehbaz
>>
>> On Sat, Apr 19, 2014 at 11:07 PM, Shehbaz Jaffer
>> <shehbazjaffer007@gmail.com> wrote:
>> > Thankyou for your reply. Live migration does seem like an interesting option
>> > to explore. I will look into it and get back if I get stuck.
>> >
>> >
>> > On Wed, Apr 16, 2014 at 6:16 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> >>
>> >> Am 15.04.2014 um 16:55 hat Shehbaz Jaffer geschrieben:
>> >> > Thankyou for your reply. I do not face the error using qemu.1.7.1
>> >> > version.
>> >> >
>> >> > 1 quick question:
>> >> >
>> >> > I want to create a qcow2 image file after my VM has completed booting;
>> >> > i.e.,
>> >> > when I boot from this new snapshot, I should directly get to my VMs
>> >> > login
>> >> > prompt. How can i create such a qcow2 snapshot?
>> >> >
>> >> > I tried stopped the VM using QMP after the VM had completed booting, and
>> >> > then
>> >> > using host CLI to create a qcow2 image :
>> >> >
>> >> > qemu-img create -b ubuntu.qcow2 -f qcow2 newsnap.qcow2
>> >> >
>> >> > This created a new qcow2 file - newsnap.qcow2 on top of ubuntu.qcow2,
>> >> > however
>> >> > when I boot using newsnap.qcow2, It takes me again through the complete
>> >> > boot
>> >> > process - till the login prompt.
>> >> >
>> >> > Is there a way to create the qcow2 snapshot after VM has completed
>> >> > booting?
>> >>
>> >> The reason for this is that you only create a snapshot of the disk this
>> >> way, not of the VM state (i.e. RAM contents, device states, etc.)
>> >>
>> >> The most convenient way when you're using qemu directly is probably
>> >> using internal snapshots. This is what the savevm/loadvm HMP commands
>> >> provide (not sure if there is a QMP equivalent); you can also use the
>> >> -loadvm command line parameter to start a VM from a snapshot.
>> >>
>> >> Another option is that you take an external snapshot in a new qcow2 file
>> >> like you did, but you additionally do a live migration into a file. When
>> >> restarting the VM, you need to use the -incoming option and feed that
>> >> file back to qemu. As this is a bit more cumbersome, this is probably
>> >> more an option for management tools than for manual use.
>> >>
>> >> Kevin
>> >
>> >
>> >
>> >
>> > --
>> > Shehbaz Jaffer
>> > MTS | Advanced Technology Group |  NetApp
>>
>>
>>
>> --
>> Shehbaz Jaffer
>> MTS | Advanced Technology Group |  NetApp



-- 
Shehbaz Jaffer
MTS | Advanced Technology Group |  NetApp