Till today everywhere I looked recommended using RDM over VMFS for performance (when a higher I/O is required), though today while studying for my VMware Design Exam I have got my hand on the “
Performance Characterization of VMFS and RDM Using a SAN” document by VMware. The interesting executive summary of the document is copied up to the letter below:
The main conclusions that can be drawn from the tests described in this study are:
- For random reads and writes, VMFS and RDM yield a similar number of I/O operations per second.
- For sequential reads and writes, performance of VMFS is very close to that of