I have two Proliant ML370 servers with VSphere 5.0, both connected to an external HP MSA2212 Fiber channel storagee.
I noticed a very poor performance when using RDM LUNs compared to VMFS. I used DiskSPD to test IOPs, throughput and average latency.
For example: LUN: 600GB - RAID 1
Test A): random reads of 8Kb blocks
Using RDM: 2 MB/sec throughput
Using VMFS: 250 MB/sec throughput
Test B): sequential reads of 512Kb blocks
Using RDM: 5 MB/sec throughput
Using VMFS: 1500 MB/sec throughput
Desperately need some help!
Did you run the test from the same source (VM) ? How is the virtual SCSI device configuration ?
Yes. I ran both tests in a new Windows 2008 VM and an existing one. In both machines the tests are the same.
SCSI controller 0: LSI Logic SAS. Bus sharing: None
Mapped RUN LUN: Physical mode.
Thanks for your time!