Overview
vVols replace LUN-based datastores formatted with VMFS. There is no file system on a vVol datastore, nor are vVol-based virtual disks encapsulated in files.
The datastore concept does not disappear entirely, however. VMs must be provisioned somewhere. Historically, VMs have typically been implemented as files in NFS mounts or in a VMFS. Datastores are necessary, both because VM provisioning tools use them to house new VMs, and because they help control storage allocation and differentiate between different types of storage.
However, VMFS datastores limit flexibility, primarily because their sizes and features are specified when they are created, and it is not possible to assign different features to individual objects in them. To overcome this limitation, the vVol architecture includes a storage container object, generally referred to as a vVol datastore, with two key properties:
Capacity limit
- Allows an array administrator to limit the capacity that VMware administrators can provision as vVols.
Array capabilities
- Allows vCenter to determine whether an array can satisfy a configuration request for a VM.
A vVol datastore is sometimes referred to as a storage container. Although the terms are essentially interchangeable, this report uses the term vVol datastore exclusively.