[CentOS-virt] Best virtualization setup for Centos 5.2

Farkas Levente lfarkas at lfarkas.org
Wed Jan 21 22:07:26 UTC 2009

Dennis J. wrote:
> 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 only found some outdated and contested data on the web and virtualization 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.

may be worth waiting a little bit more, since:
- rhel 5.3 released, so in a few weeks we'll have centos 5.3 and
according rhel's annoncement it has some virtio_net support,
- there'll be a new virt-manager and virtinst release in the near future
(according to a last week's mail) which contains rhel-5 fixes.

anyway imho xen is much more stable on rhel/centos-5 hosts then the
current kvm line. kvm will be usable on kernel-2.6.29 and since
rhel/centos-5  will be always 2.6.18 based we've towait for
rhel/centos-6 which won't be in this year:-( or you can use other distro
like fedora or ubuntu at least for host os.

  Levente                               "Si vis pacem para bellum!"

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