[PVE-User] Backups kill one guest, semi-consistently.

[Myke G]

Approximately 4 nights a week, when the backups run, the first VM in the 
list seems to hang and eventually revert to the shutdown state according 
to the Proxmox webui, but inside the VM, the filesystems are not cleanly 
shutdown. The guest is a fully virtualized instance of FreeBSD 8 
(-STABLE as of a couple weeks ago IIRC)

What's strange is that ONLY this VM gets hit, there's another other 
FreeBSD VM and a pair of OpenVZ VMs running on there too, but just this 
one seems to fail. It does happen to have the lowest VMID, I don't know 
if that's a factor.

I was actually logged into the instance when the backup kicked off this 
evening, and while SSH stayed alive, it seemed as if the filesystem was 
completely dead:

Nov 17 01:02:55 VPS1 kernel: calcru: runtime went backwards from 
79964129 usec to 71205911 usec for pid 1097 (squid)
[root at VPS1 /var/log]#
[root at VPS1 /var/log]# uptime
(nothing happens after several seconds; hit ^T a bunch...)
load: 0.00  cmd: bash 15734 [vnread] 1.35r 0.00u 0.00s 0% 2420k
load: 0.00  cmd: bash 15734 [vnread] 3.78r 0.00u 0.00s 0% 2420k
load: 0.00  cmd: bash 15734 [vnread] 4.16r 0.00u 0.00s 0% 2420k
^C^C
^C (no effect)
load: 0.00  cmd: bash 15734 [vnread] 81.93r 0.00u 0.00s 0% 2420k
load: 0.00  cmd: bash 15734 [vnread] 82.24r 0.00u 0.00s 0% 2420k

We're running a slightly dated Proxmox:

Chisel:~# pveversion -v
pve-manager: 1.5-10 (pve-manager/1.5/4822)
running kernel: 2.6.24-11-pve
proxmox-ve-2.6.24: 1.5-23
pve-kernel-2.6.24-11-pve: 2.6.24-23
pve-kernel-2.6.24-9-pve: 2.6.24-18
pve-kernel-2.6.24-8-pve: 2.6.24-16
qemu-server: 1.1-16
pve-firmware: 1.0-5
libpve-storage-perl: 1.0-13
vncterm: 0.9-2
vzctl: 3.0.23-1pve11
vzdump: 1.2-5
vzprocps: 2.0.11-1dso2
vzquota: 3.0.11-1
pve-qemu-kvm: 0.12.4-1
Chisel:~#

Any ideas or suggestions? It's getting quite frustrating to have to 
restart this VM almost every night.
(The backups do complete successfully BTW)

Myke