How Virtual Machines
Access Storage
A virtual disk
hides the physical storage layer from the virtual machine's operating system.
Regardless of the type of storage device that your
host uses, the virtual disk always appears to the virtual machine as a mounted virtual
storage device. As a result, you can run operating systems that are not certified for
specific storage equipment, such as SAN, in the virtual machine.
When a virtual machine communicates with its virtual
disk stored on a datastore, it issues virtual device interface commands appropriate for
the device. Because datastores can exist on various types of physical storage, these
commands are encapsulated into other forms, depending on the protocol that the
ESXi
host uses to connect to a storage device. Figure 1
depicts five virtual machines that use different types of storage to illustrate
the differences between each type.
Virtual Machines Accessing Different
Types of Storage

You can use ESXCLI commands to manage the virtual
machine file system and storage devices.
- Datastores - Several commands allow you to manage datastores and are useful for multiple protocols.
- LUNs - Useesxcli storage coreto display available LUNs and mappings for each VMFS volume to its corresponding partition. See Examining LUNs.
- Path management - Useesxcli storage coreto list information about Fibre Channel or iSCSI LUNs and to change a path’s state. See Managing Paths. Use the ESXCLI command to view and modify path policies. See Managing Path Policies.
- Rescan - Useesxcli storage coreto perform a rescan operation each time you reconfigure your storage setup. See Scanning Storage Adapters.
- Storage devices - Several commands manage only specific storage devices.
- NFS storage - Useesxcli storage nfsto manage NAS storage devices. See Managing NFS/NAS Datastores.
- iSCSI storage - Useesxcli iscsito manage both hardware and software iSCSI. See Managing iSCSI Storage.
- Software-defined storage - vSphere supports several types of software-defined storage.
- vSANstorage - Use commands in theesxcli vsannamespace to managevSAN. See Monitoring and Managing vSAN Storage.
- Virtual Flash storage - Use commands in theesxcli storage vflashnamespace to manage VMware vSphere Flash Read Cache.
- Virtual volumes - Virtual volumes offer a different layer of abstraction than datastores. As a result, finer-grained management is possible. Use commands in theesxcli storage vvolnamespace.