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Re: Backing up VMware-VMs
2008-03-10 16:33:31
Paul Bijnens wrote:
On 2008-03-06 21:38, Steve Wray wrote:
Stefan G. Weichinger wrote:
Patrick M. Hausen schrieb:
So if you want to backup/copy an entire VM with the guarantee of
consistent hard disk state, you need to shut it down. Copying
a multi gigabyte virtal disk file is bound to take quite some time.
So you need to power down your virtual machine for what can amount
to hours.
What about combining it with LVM-snapshots?
Are LVM snapshots working properly now?
The last few times I tried it (several months ago) it was a total
disaster and not something I'd want to risk even attempting on a
virtual machine.
What kind of disaster on which kernel?
This would have been Debian Sarge last year. I forget the exact kernel
version.
The sort of disaster where it runs out of RAM while taking the snapshot
and you are left with a kind of zombie logical volume which can't be
deleted and the system is confused about the state of the source logical
volume.
Required a reboot to fix it.
At the time I was aware that snapshots were an unsupported 'feature' in
LVM2 though so this wasn't a production system.
Snapshots had been so useful in LVM1, I still don't understand why they
had to break it in LVM2, seems like a step back to me.
Still, if the LVM crew have fix0red it I'll give it another go on a
sacrificial server...
I had problems when using LVM2 in CentOS/RHEL 4.2 or so, but in 4.5
and 5 it is stable as long as you have 256 Mbyte RAM or more (I have
one machine with 128 Mbyte RAM running CentOS 4.5, and that one had a
kernel panic once every 6 months or so due to LVM2 snapshots -- I do not
use snapshots anymore on that machine since last time it crashed
about 3 weeks ago. Most of my other servers take snapshots twice a
day (as "cheap backup" during noon, and as quiet filesystem for
nightly Amanda backups), and have no problems with it.
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