Re: [Moosefs-users] KVM (Kernel Virtual Machine) problems on the native MFS

[Jun C. P. <jun...@gm...>]

It turned out that, when I used "virsh start mfskvm1," it simply
worked well, no network issue any more. Interestingly enough, when I
manually invoked qemu-kvm with the same options, I got all weird
problems (network issue, udev fails, and so on...). So in my tentative
conclusion, "virsh start domain" does internally something more than
invoking the qemu-kvm process.

Anyway, it seems that there is a way to successfully create a KVM VM
on the native MFS although virt-manger and virt-install still do not
work well on MFS for me.

-Jun

On Tue, Dec 14, 2010 at 3:13 PM, Jun Cheol Park
<jun...@gm...> wrote:
> Hi,
>
> I have been trying to create a KVM guest VM on the native MFS. But it
> has not been quite successful although I getting closer.... Before
> delving into the problems, I would like to clarify some relevant
> issues. When I used a loop device on top of MFS using sparse files
> (For instance, mount -o loop /mnt/mfs/mfs_sparse_200g
> /mnt/mfs/loop0/), I didn't have any problems in using KVM on
> /mnt/mfs/loop0/).
>
> The problems that I am experiencing now are from the cases where I try
> to create KVM guest VMs directly on the native MFS. Here I hope to get
> any successful story as to how to **manually** setup a KVM guest OS on
> the native MFS without using virt-manager or virt-install because
> those tools didn't work on the native MFS.
>
> The following are the details of the problems.
>
> First I made an MFS mountpoint on a KVM node (and MFS client) as follows.
> # mfsmount -H $metadata_server_ip -o suid -o dev -o rw -o exec /mnt/mfs
> # mount
> ...
> mfs#$metadata_server_ip:9421 on /mnt/mfs type fuse
> (rw,allow_other,default_permissions)
>
> Then, create a disk image file for the guest storage.
> # qemu-img create -f qcow2 /mnt/mfs/mfskvm1.img 10G
> # virt-install --name CentOS5 --ram 1000 --disk
> path=/mnt/mfs/mfskvm1.img,size=10 --network network:default
> --accelerate --vnc --cdrom /mnt/mfs/CentOS-5.5-x86_64-bin-DVD-1of2.iso
> --os-type=linux
>
> Then, I got the following error:
>
> Starting install...
> ERROR    internal error unable to start guest: qemu: could not open
> disk image /mnt/mfs/mfsvkm1.img
>
> So it seems that the given KVM management tools including virt-install
> and virt-manager are not working well directly on the native MFS
> because (I guess) there are some incompatible options used by those
> tools, which conflicts with MFS.
>
> Then, I tried to manually create a KVM on the naitve MFS as follows
> via qemu-kvm.
>
> # /usr/libexec/qemu-kvm -M rhel5.4.0 -m 1024 -smp 1 -name mfskvm1
> -uuid af1be3ae-daab-d450-293b-dc03ff7c3c35 -no-kvm-pit-reinjection
> -monitor pty -pidfile /var/run/libvirt/qemu/mfskvm1.pid -no-reboot
> -boot d -drive file=/mnt/mfs/mfskvm1.img,if=virtio,index=0,format=qcow2,cache=writethrough
> -drive file=/mnt/mfs/CentOS-5.5-x86_64-bin-DVD-1of2.iso,if=ide,media=cdrom,index=2,format=raw,cache=writethrough
> -net nic,macaddr=12:01:77:99:00:20,vlan=0,model=e1000 -net
> tap,fd=33,script=,vlan=0,ifname=vnet0 -serial pty -parallel none -usb
> -usbdevice tablet -vnc :10 &
>
> Then, it worked well! The differences from virt-manager or
> virt-install are here I use 'cache=writethrough' rather than 'none'
> and don't use '-S' as opposed to the options generated by virt-manager
> virt-install. So I could successfully installed CentOS.iso on
> mfskvm1.img, and then rebooted it, which resulted in the qemu-kvm
> process gone due to the option of -no-reboot.
>
> Then, I invoked the qemu-kvm process in order to boot up mfskvm1 using
> the installed image on mfskvm1.img as follows:
>
> # /usr/libexec/qemu-kvm -M rhel5.4.0 -m 1024 -smp 1 -name mfskvm1
> -uuid af1be3ae-daab-d450-293b-dc03ff7c3c35 -no-kvm-pit-reinjection
> -monitor pty -pidfile /var/run/libvirt/qemu/mfskvm1.pid -boot c -drive
> file=/mnt/mfs/mfskvm1.img,if=virtio,index=0,boot=on,format=qcow2,cache=writethrough
> -drive file=,if=ide,media=cdrom,index=2 -net
> nic,macaddr=12:01:77:99:00:20,vlan=0,model=e1000 -net
> tap,fd=34,script=,vlan=0,ifname=vnet0 -serial pty -parallel none -usb
> -usbdevice tablet -vnc :10 &
>
> Everything works fine except for the problem that the ip determination
> for eth0 fails. As I mentioned, when I used virt-install on the MFS
> **loop** device, the IP determination worked well, which means my dhcp
> server properly responded.
>
> I would like to get some information how to resolve this network setup
> issue on the native MFS.
>
> Thanks in advance,
>
> -Jun
>