New in vSphere are ParaVirtualized SCSI drivers. From what I have read at various places, 12% performance throughput increase with 18% decrease on guest CPU loads! Sounds great – What’s the catch?
Seems the new PVSCSI drivers are not supported for boot drives on the VMs (Chalk up one more reason to NOT have just a C drive). The situations I am running into are that many clients HAVE already moved to a single drive server model. Many of the environments I am running into have settled on a server standard consisting of a 25 – 40 GB C drive for both OS and data. For most of the infrastructure servers, this model seems to have worked out nicely. Run out of room?; just grow those puppies without breaking a sweat! Performance on these grossly underutilized servers does not seem to be a factor. A nice balance of performance vs. manageability.
At first glance, I figured I would be rolling out just about every VM with these new PVSCSI drivers, now, I think it will probably be the exception. PVSCSI will be a potential tool in my belt to help solve VM performance issues when the LSI is not up to the job. I think some of the selection criteria for when I will use PVSCSI will be server’s with applications that naturally lends itself to a multiple drive partition layout (think Mail and Database applications) in which adding PVSCSI drivers to the second, third and remaining drives will be a no brainer. For the vast majority of my VMs though, chugging happily along at 10% utilization, the LSI Logic Parallel driver will probably fit the bill.
How bout You? :)