20 Server Virtualization Terms

Many of you have heard the term “virtualization”.  These are some good terms to know related to server virtualization and VMware.

VM: Virtual Machine. ESXi: The vSphere Hypervisor from VMware. vmkernel: Officially the “operating system” that runs ESXi and delivers storage networking for VMs.  VMFS: Virtual Machine File System for ESXi hosts, a clustered file system for running VMs. iSCSI: Ethernet-based shared storage protocol. SAS: Drive type for local disks (also SATA). FCoE: Fibre Channel over Ethernet, a networking and storage technology. HBA: Host Bus Adapter for Fibre Channel storage networks. IOPs: Input/Outputs per second, detailed measurement of a drive’s performance. VM Snapshot: A point-in-time representation of a VM. ALUA: Asymmetrical logical unit access, a storage array feature.  NUMA: Non-uniform memory access, when multiple processors are involved their memory access is relative to their location. Virtual NUMA: Virtualizes NUMA with VMware hardware version 8 VMs. LUN: Logical unit number, identifies shared storage (Fibre Channel/iSCSI). pRDM: Physical mode raw device mapping, presents a LUN directly to a VM. vRDM: Virtual mode raw device mapping, encapsulates a path to a LUN specifically for one VM in a VMDK. SAN: Storage area network, a shared storage technique for block protocols (Fibre Channel/iSCSI). NAS: Network attached storage, a shared storage technique for file protocols (NFS). NFS: Network file system, a file-based storage protocol. DAS: Direct attached storage, disk devices in a host directly.