What is the difference in performance between VM storage that created on SAN and use storage directly on SAN to read and write data?
I mean, we have SQL server that is installed on VM-basis and use a virtual hard drive.
The VM is on my SAN.
Is it better to address SQL server to read and write data to SAN directly? Has my solution a better performance?
Best Answer
When it comes to performance delta between a VM-based server comparing to a bare-metal one, it’s clear the performance of bare-metal solution should be better, since it has literally fewer abstraction layers thus less penalty impact on I/O operations. It’s true for the case where a simple VHD is used. However, there is an option to increase the VM performance with help of block level iSCSI storage. VM uses iSCSI storage delivers faster performance since I/O are performed as it would be done on hardware directly.
For the case, you can take a look at StarWind Virtual SAN, HPE VSA, and UnityVSA that provides iSCSI storage. I can recommend StarWind since it runs with the speed of DAS storage, however, StarWind delivers more efficient DAS performance utilization with DRAM and SSD cache enabled.