VMware vSphere 5.1 – VMDK versus RDM
It seems the debate between using a VMDK on VMFS or an RDM still rages when it comes to the question which one is better for performance.
The VMware team has published a lot of evidence in the past that the difference is very minor, in fact difficult to measure accurately and probably unperceivable to customers. Definitely not worth giving up the value of encapsulating a VM.
Published Dec 7, 2007 (on ESX 3.0.1)
Published Feb 13, 2008 (on ESX 3.5)
Let’s take a look at some new internal data for vSphere 5.1 that continues to validate that VMDK is the right default choice.
To learn more and to read the entire article at its source, please refer to the following page, vSphere 5.1 – VMDK versus RDM- Uptime (VMware and Business Continuity)