Hi, we are running Centos 5.2 on our servers for some time now and are really happy with it. Now I'm investigating the best way to setup virtual machines in order to streamline our infrastructure. The setup I'm aiming for is Centos 5.2 guests on Centos 5.2 host. The physical systems are going to be 2xquad core Xeons and the VMs are probably going to be 1 or 2 vCPUs with 1 or 2 gb of ram for each guest. I plan to migrate a number of vmware instances on such a setup so I'm wondering what I can expect performance-wise when switching to either Xen or KVM.
As far as I understand is Xen is the "official" supported solution with Centos 5. I downloaded the KVM kernel module and some tools from a repo at lfarkas.org (unfortunately the new virt-manager there cannot be installed due to depency issues) to experiment with KVM which works so far but gives me weird results. Doing a "hdparm -t" on the host system consistently gives me a result of about 70MB/sec yet in a KVM guest I get results ranging from 40MB/sec to 125MB/sec on each run.
Also the Centos kernel does not support the virtio drivers needed for KVM paravirtualization so I'm wondering how fast hardware assisted block-io under KVM is compared to the performance of the paravirtualized Xen driver and to vmware esx based guests.
Are there any current performance benchmarks out there? I googled a bit but only found some outdated and contested data on the web and virtualization is a rather fast-moving field.
Regards, Dennis