Boot script

Hello,

my server runs XEN with 5 domains at the moment. I will get new hardware this week and I think about trying to do the virtualisation using KVM.

Xen has small scripts which

* set up the bridged network at boot
* start all domains at boot time (or restore saved domains)
* save the domains at shutdown

Are there such scripts for KVM? I would like to have an init script which does all the things listed above.

Is this even possible with qemu/kvm (save/restore a domain using shell commands)?

Thanks

Matthias

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trivially easy. in fact, it's easier to write a script than to do it by hand.

from trivial to moderate, depending on the disk layout.

moderately tricky. you'd have to put the kvm control console somewhere your shutdown script could find them, and send the 'savevm' commands.

i haven't seen any one, i feel it should be done for your specific requirements.

totally possible. restore is just a commandline switch (or automatic if using qcow images). savevm is a control command, so you'll have to redirect the control to a pipe; then the script would simply do an "echo 'savevm;quit' > kvm-xx.pipe"

Javier

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I just manually configure a bridge through my distro's networking scripts. I've got what I do fully documented at
http://kvm.qumranet.com/kvmwiki/AnthonyLiguori/Networking

You can also use libvirt to manage KVM in which case, it will automagically configure networking for you.

I just use a script in /etc/init.d/ that I wrote but libvirt will also do this for you.

As in, do a save at shutdown? That seems pretty scary to me. I don't know what libvirt does on shutdown but I'm sure someone can chime in.

You have two options. If you use libvirt, you can issue commands via virsh. If you don't use libvirt, you need to have the monitor sit on a unix domain socket or on a TCP socket and you can issue commands to the monitor via a tool like socat.

libvirt is by far the simplest choice for managing KVM but it's possible to do these things without it.

Regards,

Anthony Liguori

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