Vmware and SCSI

I have read in a few places that when using VMware you should use a SCSI drive for the best performance.  Are they saying use real SCSI hardware, or create a VM with virtual SCSI drives?  

If its just virtual SCSI drives why does it make a difference?
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vmwarun - ArunConnect With a Mentor Commented:
By default VMware only supports SCSI, SATA and SAS Drives in ESX Hosts.

VMware has got 2 environments for running Virtual Machines - Hosted Environment and Bare Metal Hardware Environment.

Hosted Environment includes products such as VMware Workstation, VMware Server and VMware Fusion.

Bare Metal Hardware Environment includes ESXi/ESX Hosts.

If you are intending to run your VIrtual machines only in Hosted Environment, you can use IDE or SCSI but if you intend to move your VMs to Bare Metal Hardware Enviroment, IDE is not supported.

For this reason, either SCSI, SATA or SAS is recommended.
crokeefe28Connect With a Mentor Commented:
Real SCSI, but that would only be for local VMDK's.  FC would be the prefered if you can afford it, or maybe SAS.
3nerdsConnect With a Mentor Commented:
The simple answer behind everything that the 2 people above me have stated which is all true is that.

SCSi can perform a read and a write in one clock cycle where as SATA and older IDE can only perfrom either a read or a write in that same clock cycle. So if you have high input output like databases SCSI provide an almost 2 to 1 advantage. In the real world it isn't  a 2 to 1 improvement but you do see a good advantage.


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