Paravirtualized Disks in VMware, VirtualBox, XEN/KVM: Do they support NCQ?
Paravirtualized disks are a popular choice for virtualization platforms such as VMware, VirtualBox, XEN, and KVM. NCQ (Native Command Queuing) is a feature present in modern hard drives and SSDs that allows for the reordering of commands to optimize performance. However, the support for NCQ in paravirtualized disks can be complex and is dependent on the underlying physical disk's NCQ support passing through virtualization queued depth.
Understanding Paravirtualized Disks
Paravirtualized disks are a type of virtual disk that allows the guest operating system to be aware that it is running in a virtual environment. This awareness enables the guest OS to communicate directly with the hypervisor, bypassing the need for emulation. This results in improved performance and reduced overhead compared to fully virtualized disks.
NCQ Support in Paravirtualized Disks
NCQ support in paravirtualized disks is dependent on the underlying physical disk's NCQ support passing through virtualization queued depth. This means that if the physical disk supports NCQ, and the virtualization platform supports passing through the NCQ commands, then the paravirtualized disk can take advantage of NCQ.
NCQ Support in VMware
VMware supports NCQ pass-through for paravirtualized disks in certain versions of its vSphere and ESXi products. However, the support is dependent on the underlying physical disk and storage controller, as well as the version of VMware being used.
NCQ Support in VirtualBox
VirtualBox supports NCQ for paravirtualized disks in certain versions. However, the support is dependent on the underlying physical disk and storage controller, as well as the version of VirtualBox being used.
NCQ Support in XEN/KVM
XEN and KVM both support NCQ for paravirtualized disks, but the support is dependent on the underlying physical disk and storage controller, as well as the version of XEN or KVM being used.
NCQ support in paravirtualized disks is dependent on the underlying physical disk's NCQ support passing through virtualization queued depth. VMware, VirtualBox, XEN, and KVM all support NCQ for paravirtualized disks, but the support is dependent on the version of the virtualization platform and the underlying physical disk and storage controller.
References
- VMware vSphere 6.5 Documentation: Paravirtual SCSI Adapter
- VirtualBox Manual: Paravirtualized SCSI Controllers
- Xen PCI Passthrough Wiki
- Red Hat: KVM Virtualization
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