Grant McWilliams

To convert a QEMU qcow format disk to VirtualBox vdi format you need to have Qemu installed. Qemu has tools to help convert disk formats.

grant@workstation:~$ qemu-img convert hda-qcow.img -O raw hda.img

grant@workstation:~$ VBoxManage convertdd hda.img hda.vdi
VirtualBox Command Line Management Interface Version 1.6.0
(C) 2005-2008 Sun Microsystems, Inc.
All rights reserved.

Converting VDI: from DD image file="hda.img" to file="hda.vdi"...
Creating fixed image with size 1024966656 bytes (978MB)...

This will convert a QEMU qcow format disk image to VirtualBox vdi format.

This isn't really a howto per se but rather a pointer to RPMs for KVM on CentOS/RHEL.

You can get KVM 80 for x86_64 here.

http://www.lfarkas.org/linux/packages/centos/5/x86_64/

The same site doesn't seem to have i386 RPMs but they do have i386 SRPMS that you could build.

http://www.lfarkas.org/linux/packages/centos/5/SRPMS/

I don't have time to do any sort of tutorial on building KVM SRPMs because I'm not currently using KVM for any projects. In the future I'll get to it but probably not too soon.

I don't generally use KVM so the Howto's here are old and probably obsolete.

So here's a quick howto on getting KVM to work on CentOS5.x. I'll add more tutorials when I start using KVM more. For now I spend all my time on VirtualBox at work and Xen everywhere else. KVM is maturing fast but still not where Xen is for the most part. It also needs VT support in the CPUs which means not everyone can use it. My 4 core, 8 vcpu Xeon machine in the garage won't run KVM so I'm not spending a lot of time with it right now. One of the reasons I don't use KVM in a production environment is it moves too fast and the distros are just too far behind as you'll see in the howto

1. First you need to see if you're CPU has the needed hardware VT support

egrep 'vmx|svm' /proc/cpuinfo

If you have an Intel CPU with VT support you should get back vmx and svm if it's AMD with VT support. If you get nothing you need to use Xen or VirtualBox as both support Virtualization without the hardware VT support.

2. Install KVM and QEMU

yum install kvm kmod-kvm qemu

The current version of KVM is 36 which is ancient (August 2007) but stable as far as KVM goes. Even with this version I've gotten lockups and strange behavior. The most recent version of KVM is 74 so you can imagine what's been added since version 36. If you want to check it out yourself here's the changelog.

The problem with Virtualization systems is none of them want to standardize on one particular disk format. Actually they all do, they want their format to be the standard.

• VMware has VMDK
• QEMU has qcow and qcow2
• UML has cow
• Parallels has HDD
• VirtualPC uses VHD
• VirtualBox has VDI
• Xen uses raw disk images

To make matters more confusing VirtualBox has some support for VMDK, Commercial Xen supports VHD, the open source Xen supports qcow2 and Qemu can convert between many formats. So what I'm doing about this is putting up a series of Howtos in the Tech -> Virtualization areas on how to convert and use various disk formats in different Virtualization systems. To start with I just put together the following two Howtos.