Overview

vVols are VMDK granular storage entities exported by storage arrays. vVols are exported to the ESXi host through a small set of protocol end-points (PE). Protocol Endpoints are part of the physical storage fabric, and they establish a data path from virtual machines to their respective vVols on demand. Storage systems enable data services on vVols. The results of these data services are newer vVols. Data services, configuration and management of virtual volume systems is exclusively done out-of-band with respect to the data path. vVols can be grouped into logical entities called storage containers (SC) for management purposes. The existence of storage containers is limited to the out-of-band management channel. 
 
vVols and Storage Containers (SC) form the virtual storage fabric. Protocol Endpoints (PE) are part of the physical storage fabric. 
 
By using a special set of APIs called vSphere APIs for Storage Awareness (VASA), the storage system becomes aware of the vVols and their associations with the relevant virtual machines. Through VASA, vSphere and the underlying storage system establishes a two-way out-of-band communication to perform data services and offload certain virtual machine operations to the storage system. For example, operations such as snapshots and clones can be offloaded.
 
For in-band communication with vVols storage systems, vSphere continues to use standard SCSI and NFS protocols. This results in support with vVols for any type of storage that includes iSCSI, Fibre Channel, Fibre Channel over Ethernet (FCoE), and NFS.

 

 

vVols Component Overview

 

A vVols storage provider, also called a VASA provider is a software component that acts as a storage awareness service for vSphere. The provider mediates out-of-band communication between the vCenter Server and ESXi hosts on one side and a storage system on the other.

• Software component developed by Storage Array Vendors.
• ESX and vCenter Server connect to VASA Provider.
• Provides Storage awareness services.
• Single VASA Provider can manages multiple arrays.
• Supports VASA APIs exported by the ESXi host.
• VASA Provider can be implemented within the array’s management server or firmware.
• Responsible for creating vVols.

Unlike traditional LUN and NFS based vSphere storage, the vVols functionality does not require pre-configured volumes on a storage side. Instead, vVols uses a storage container, which is a pool of raw storage capacity or an aggregation of storage capabilities that a storage system can provide to vVols.

• Logical storage constructs for grouping of vVols.
• Logically partition or isolate virtual machines with diverse storage needs and requirement.
• A single Storage Container can be simultaneously accessed via multiple Protocol Endpoints.
• Desired capabilities are applied to the Storage Containers.
• VASA Provider discovers Storage Container and reports to the vCenter Server.
• Any new virtual machines that are created are subsequently provisioned in the Storage Container.

 

Although storage systems manage all aspects of vVols, ESXi hosts have no direct access to vVols on the storage side. Instead, ESXi hosts use a logical I/O proxy, called the Protocol Endpoint (PE), to communicate with vVols and virtual disk files that vVols encapsulate. ESXi uses Protocol Endpoints (PE) to establish a data path on demand from virtual machines to their respective vVols.

• Separate the access points from the storage itself.
• Can have fewer access points.
• Existing multi-path policies and NFS topology requirements can be applied to the PE.
• Access points that enables communication between ESXi hosts and storage array systems.
• Compatible with all SAN and NAS Protocols: iSCSI, NFS v3, FC, FCoE.
• A Protocol Endpoint can support any one of these protocols at a given time.