LSI vs Buslogic (ESX/ESXi 3.x and 4.x)
In ESX 3.x there are only two different type of virtual SCSI adapters: Buslogic and LSI Logic (new from ESX 2.x)
The backend for Buslogic / LSILogic is almost identical, with very minor differences due to the hardware specs being different. The differences only apply during device driver loading, and should not affect I/O speed.
The real reason for two controllers is driver support. Older OSes have default driver support for Buslogic (e.g. Windows 2000 install CD), newer OSes do not have Buslogic drivers but do have LSILogic drivers (e.g. Windows 2003, 2008 install CDs). Pick the controller for which it is easier to obtain a driver for the guest.
Windows 2000 has by default the BusLogic driver, and Windows 2003 the LSI Logic.
For Linux in most cases, VMware recommends that you use the LSI Logic virtual SCSI adapter with all Red Hat guest operating systems. However, ESX Server 2.5.2, 2.5.3, 2.5.4, and 2.5.5 support only the BusLogic SCSI adapter. VMware provides a separate BusLogic driver for Red Hat Enterprise Linux 4 Upgrades 1, 2, 3, 4, and 5 (see http://www.vmware.com/files/pdf/linux_install_config.pdf).
To change adapter type:
http://kb.vmware.com/kb/1002149 - Changing the virtual SCSI controller of a virtual machine
Possible performance issues with Buslogic virtual adapter:
http://kb.vmware.com/kb/1614 - Effective BusLogic Qdepth is Limited to One on Windows 2000 SP3, 2003, or XP
http://kb.vmware.com/kb/1890 - Limited Disk Throughput from Windows with BusLogic Adapter Causes Performance Problems
http://kb.vmware.com/kb/1306 - NOT_IMPLEMENTED Errors in Windows NT, 2000, XP, and Server 2003 Virtual Machines on ESX Server 2.0 and 2.1
Possible problem with LSILogic:
http://kb.vmware.com/kb/1006224 - Windows Guests Installed with LSI Logic Storport Driver 1.26.05 Crash while Booting
And here is some LSILogic tuning knobs to play with that I haven't made time to test yet:
http://kb.vmware.com/kb/9645697 - Large I/Os Are Split into 64KB Units When Using LSILogic Driver
Benchmark test on this different controller:
New adapters (ESX/ESXi 4.x)
With vSphere there are two new virtual SCSI adapters: LSI logic SAS and VMware Paravirtualized (PVSCSI).
The old adapters are now called: LSI logic parallel and Buslogic parallel.
New adapters are available for VM with Hardware version 7 only. The main difference is: LSI Parallel is more compatible and work on most systems, while LSI SAS and VMware paravirtual are faster.
Note that in vSphere there is also a IDE adapter for legacy support (for example for old OS).
LSI Logic SAS is intended for use with Windows 2008 only for clustering.
For PVSCSI see:
http://kb.vmware.com/kb/1010398 - Configuring disks to use VMware Paravirtual SCSI (PVSCSI) adapters
Know problem with PVSCSI:
Note that in vSphere 4.0 VMware doesn’t support using the PVSCSI adapter for boot devices. That is not to say that it doesn’t work (it does work), but that it is not supported.
With vSphere 4.0U1 this controller is now supported also for boot devices in Windows 2003 and 2008 guests.