[CentOS] Really bad KVM disk performance

[Gordon Messmer]

On 02/19/2012 09:26 PM, Bob Puff wrote:
>
> Immediately when I was installing stuff, I could tell this new system I just
> built was not nearly as fast as the first one.  I ran some CPU and disk
> benchmarking programs, and saw that while the CPU stuff tested similarly, the
> disk thruput was much different... Down-right poor in one of the guests!

If you use Red Hat's "virt-install" to set up a guest, you can specify 
the --os-type and --os-variant.  If you specify the a variant that 
supports virtualized IO (such as type: linux and variant: rhel5.4 or 
rhel 6), the guest's disk and network IO will have much better 
throughput.  You'll want to look for those options in whatever front-end 
you're using, or use virt-install.