[libvirt] [BUG] Managed save qemu state gets deleted after failed resume

[Eric Blake]

On 03/30/2011 02:24 AM, Philipp Hahn wrote:
> Hello,
> 
> I haven't had time to provide a fix, but still want you to inform you about a 
> bug: If resuming a saved VM fails with Qemu-0.14, the managed save state 
> file /var/lib/libvirt/qemu/save/$VM.save is still deleted. I think it would 
> be better to only delete the state after an successful resume.

Then we would get multiple failures on every resume attempt.  However, I
tend to agree with you that data loss in any form is bad, and this is a
form of data loss.

> -device usb-tablet,id=input0 -vnc 0.0.0.0:5 -k de -vga cirrus -device
> virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -option-rom
> /usr/share/kvm/pxe-rtl8139.bin
> Failed to allocate 2147483648 B: Cannot allocate memory

Especially bad that it looks like a transient ENOMEM condition can cause
the data loss (that is, if I'm interpreting your log correctly, then you
can trigger this condition by temporarily consuming too much memory in
the host, trying to resume a target, then reducing memory pressure, and
try to resume again but now you've lost the state file to resume from).

> 
> This issue is tracked in our (German) bug-tracker at 
> <https://forge.univention.org/bugzilla/show_bug.cgi?id=22021>

Thanks for the link.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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