vsphere-esxi-vcenter-server-55-storage-guide

Chapter 1 Introduction to StorageNetwork-attached Storage (NAS)Stores virtual machine files on remote file servers accessed over a standard TCP/IP network. The NFS clientbuilt into ESXi uses Network File System (NFS) protocol version 3 to communicate with the NAS/NFSservers. For network connectivity, the host requires a standard network adapter.NOTE ESXi does not support the delegate user functionality that enables access to NFS volumes using nonrootcredentials.NFS Storage depicts a virtual machine using the NFS volume to store its files. In this configuration, the hostconnects to the NFS server, which stores the virtual disk files, through a regular network adapter.Figure 1‐4. NFS StorageHostvirtualmachineethernetNICLANNFSNAS applianceShared Serial Attached SCSI (SAS)Stores virtual machines on direct-attached SAS storage systems that offer shared access to multiple hosts.This type of access permits multiple hosts to access the same VMFS datastore on a LUN.Target and Device RepresentationsIn the ESXi context, the term target identifies a single storage unit that the host can access. The terms deviceand LUN describe a logical volume that represents storage space on a target. Typically, the terms device andLUN, in the ESXi context, mean a storage volume presented to the host from a storage target and availablefor formatting.Different storage vendors present the storage systems to ESXi hosts in different ways. Some vendors presenta single target with multiple storage devices or LUNs on it, while others present multiple targets with oneLUN each.VMware, Inc. 17