How to do an automated backup?

How to do an automated backup?

[Steve Lorimer]

Ok, should be a simple question here:  How to backup a KVM host image.

My first plan - failure:
1) Suspend / hibernate (using virsh ... save) image to disk
2) Backup vm disk image & suspend file
3) Backup .xml
4) Restore suspended image
This would accomplish a backup that could be reactivated very quickly as 
bootup would not even be required.
However, in testing it failed.  Of two VM's tried, one worked, but the 
other one never came back up.  The network interface never reenabled and 
this system itself sat maxing out it's cpu core until manually terminated.

My second plan:
1) Use virsh to shutdown the VM
2) Backup vm file & xml
3) Start vm (regular bootup)
This takes longer, but can be tolerated in order to get a backup.  
However, this fails also:
virsh -c qemu:///system shutdown kvmtest
The command fails to send any kind of shutdown request to the VM guest.  
As a result, the only thing that works is to kill it (the virsh command 
for that does work).  However, this is not acceptable for a backup.

Nothing out of the ordinary in my system setup:
VM Server:  Ubuntu Server
Guest OS's: Also Ubuntu

Any thoughts, advice?

Re: How to do an automated backup?

[Javier Guerra]

On Mon, Nov 3, 2008 at 2:32 PM, Steve Lorimer <slorimer@kmbc.edu> wrote:
> Ok, should be a simple question here:  How to backup a KVM host image.

this is far from a simple question.

it appears periodically on the Xen lists.  with few exceptions, the
best advice is to use traditional network backup software "from
inside" the guests.

-- 
Javier

Re: How to do an automated backup?

[Chris Lalancette]

Steve Lorimer wrote:
> Ok, should be a simple question here:  How to backup a KVM host image.
...
> My second plan:
> 1) Use virsh to shutdown the VM
> 2) Backup vm file & xml
> 3) Start vm (regular bootup)
> This takes longer, but can be tolerated in order to get a backup.  
> However, this fails also:
> virsh -c qemu:///system shutdown kvmtest
> The command fails to send any kind of shutdown request to the VM guest.  
> As a result, the only thing that works is to kill it (the virsh command 
> for that does work).  However, this is not acceptable for a backup.

"virsh shutdown" should work, provided you have a new enough version of libvirt
(what version are you using?), you have the <acpi/> tag set in the libvirt XML,
and your guest (what kind of guest is it?) is using ACPI.  virsh shutdown works
by sending an ACPI event to the guest, basically equivalent to hitting the soft
power button on a piece of hardware.  In recent testing, I was able to use virsh
shutdown to shut down basically any 2.6 based Linux guest, and any Windows guest
using ACPI.

That said, doing the backup "inside" the guest, as suggested by Javier, is
probably a better solution.

-- 
Chris Lalancette

RE: How to do an automated backup?

[Martin Maurer]

> -----Original Message-----
> From: kvm-owner@vger.kernel.org [mailto:kvm-owner@vger.kernel.org] On
> Behalf Of Steve Lorimer
> Sent: Montag, 03. November 2008 20:32
> To: kvm@vger.kernel.org
> Subject: How to do an automated backup?
> 
> Ok, should be a simple question here:  How to backup a KVM host image.

Hi,

Maybe you take a look to our Proxmox VE 1.0, including a GUI for doing scheduled KVM backups (with vzdump). Maybe you can pick some points for your, or you just move to Proxmox VE as we already solved this.
You find all infos on http://pve.proxmox.com 

Best Regards,

Martin Maurer

martin@proxmox.com
http://www.proxmox.com

 

Re: How to do an automated backup?

[Avi Kivity]

Steve Lorimer wrote:
> Ok, should be a simple question here:  How to backup a KVM host image.
>
> My first plan - failure:
> 1) Suspend / hibernate (using virsh ... save) image to disk
> 2) Backup vm disk image & suspend file
> 3) Backup .xml
> 4) Restore suspended image
> This would accomplish a backup that could be reactivated very quickly 
> as bootup would not even be required.
> However, in testing it failed.  Of two VM's tried, one worked, but the 
> other one never came back up.  The network interface never reenabled 
> and this system itself sat maxing out it's cpu core until manually 
> terminated.
>

That's a bug.  If you can reproduce this on the latest kvm, and provide 
instructions for us on how to reproduce this, we will try to fix it.

> My second plan:
> 1) Use virsh to shutdown the VM
> 2) Backup vm file & xml
> 3) Start vm (regular bootup)
> This takes longer, but can be tolerated in order to get a backup.  
> However, this fails also:
> virsh -c qemu:///system shutdown kvmtest
> The command fails to send any kind of shutdown request to the VM 
> guest.  As a result, the only thing that works is to kill it (the 
> virsh command for that does work).  However, this is not acceptable 
> for a backup.
>
> Nothing out of the ordinary in my system setup:
> VM Server:  Ubuntu Server
> Guest OS's: Also Ubuntu
>
> Any thoughts, advice?

If your backing store supports snapshots (btrfs, lvm) you could create a 
snapshot while the guest is running, and backup the snapshot.

The integrity of the backup depends on whether the guest is able to 
recover from restarts.

-- 
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