Added by default during VM creation, the storage controller is used to access virtual disks, CD/DVD devices, and SCSI devices. Storage controllers are presented to VMs as different types of storage controllers, such as BusLogic Parallel, LSI Logic Parallel, LSI Logic SAS, VMware Paravirtual SCSI, AHCI, SATA, and NVMe.

Generally, the default controller optimized for best performance is assigned to the VM based on the guest OS selection, the device type, and VM compatibility. A maximum of four SATA, four SCSI, and four NVMe controllers are supported for each VM. If, during the creation of the VM, the Windows Server 2008 or 2012 guest OS is selected, for example, the LSI Logic SAS controller is assigned by the system.

The following list contains the options that are available today (visit https://blogs.vmware.com/vsphere/2014/02/vscsi-controller-choose-performance.html for more information):

• BusLogic: This was one of the first emulated vSCSI controllers available in the VMware platform.
• LSI Logic Parallel (formerly known as just LSI Logic): This was another emulated vSCSI controller available initially in the VMware platform.
• LSI Logic SAS: This is an evolution of the parallel driver to support a new future-facing standard.
• VMware Paravirtual (also known as PVSCSI): This has been designed to support a very high throughput with minimal processing costs. The vSCSI controller is virtualization-aware and is, therefore, the most efficient driver.

When a VM is created, two storage controllers are assigned by default:

• SATA: This controller is assigned to access CD/DVD devices and supports up to 30 devices. If you have multiple disks, to distribute the load and improve performance, you can add up to four controllers per VM. An AHCI SATA controller is supported for VMs with ESXi 5.5 and later compatibility. A SATA controller is supported by most guest OSes and is assigned by default to CD/DVD devices.
• SCSI: Depending on the guest OS, many VMs have this controller configured by default. A single controller supports up to 15 devices. If you have multiple disks, to distribute the load and improve performance, you can add up to four controllers per VM. In the new SCSI controller, you can enable SCSI bus sharing to allow the virtual disk to be shared by the VM, for example, for building a guest cluster. There are three options available:
  • None: The virtual disk cannot be shared
  • Physical: The virtual disk can be shared by a VM on the same host
  • Virtual: The virtual disk can be shared by a VM on any host