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VVOLs and VASA Provider

VASA Provider for clustered Data ONTAP provides the tools you need to create and manage VMware virtual volumes (VVOLs). VVOLS are software-defined storage that simplify storage management. A VVOL tells the vCenter Server what the storage can do; however, it does not create objects that make up the storage.

When you use VVOLs, you can manage your storage at the virtual machine level instead of the datastore level. Doing this gives you more control of the virtual machine granular operations. In addition, when you create a virtual machine in a VVOLs environment, you have more flexibility than when you create a traditional virtual machine.

VVOLs and traditional virtual machines

With traditional virtual machines, a datastore is either a LUN (VMFS) or a volume (NFS). It is protocol-aware and can be associated with only one storage capability profile. If you use a VM Storage Policy when you provision a virtual machine, the vCenter Server selects compatible datastores based on the one storage capability profile that is associated with each datastore.

In a VVOL environment, the datastore is decoupled from the underlying storage and treated as a virtual storage system. As a result, all the storage capability profiles that can be used on a virtual disk are displayed. Each storage capability profile is associated with one or more FlexVols (or flexible volumes). The storage capability profile describes the attributes of the storage provided by the FlexVol, Storage Virtual Machine (SVM, formerly known as Vserver), or storage cluster. Then, you can create a VM Storage Policy for a VVOL datastore by selecting one of the following:

The selected VMware storage policy is pushed down to the storage array when you provision a VVOL datastore. Doing this creates the virtual disk as a storage object on an appropriate FlexVol with all the capabilities specified in the policy.

You must have VASA Provider running to use VVOLs. VASA Provider creates the swap VVOL when the virtual machine is powered on. If VASA Provider is not running, the VVOL cannot power on its virtual machines.

Note: You should not run VASA Provider on a VVOL datastore. Any management operation, including powering on a virtual machine that is on a VVOL, requires that VASA Provider be running. In addition, you would lose access to all VVOLs because VASA Provider would not be able to boot.

VVOLs benefits

Some of the benefits of VVOLs include:

The VM Storage Policies consist of sets of capabilities provided by storage. When you have policies set up, the VMware administrators can use them and do not need the detailed knowledge of the storage environment that a storage administrator must have. The policies control the placement of the virtual machines and virtual disks. You can apply a policy to a virtual machine or a virtual disk, and that object displays the correct storage. If the vCenter Server performs a compliance check and determines that the storage is no longer in compliance with the policy, it notifies you.

Storage capability profiles that you create with VASA Provider can be included in a VMware policy or can be set up separately. A storage administrator can set up a profile, and the VMware administrator can then map it into a VM Storage Policy or assign it to datastores.

Components that make up a VVOL

A VVOL is a storage object that contains parts of a virtual machine, such as virtual disks, configuration files, swap files, data files, and memory files. If you are using a block protocol then all the VVOLs must be LUNs. If you are using NFS, then some of the VVOLs are files with essentially the same content and format as equivalent LUN VVOLs and some VVOLs are directories.

A VVOL storage container must have at least one FlexVol. A single VVOL can have multiple FlexVols that have different storage capability profiles assigned to them or are on different aggregates with different disk types. All the FlexVols within a VVOL must be on the same SVM and use the same protocols. Because FlexVols have LUN count restrictions that limit the virtual machines, having multiple FlexVols can increase performance.
Note: While a storage container does not support multiple protocols, it can reside on an SVM that supports multiple protocols.

Protocol Endpoints

VVOLs are accessed using Protocol Endpoints (PEs), which are essentially small LUNs. VASA Provider creates the PE when you create a VVOL datastore in a SAN environment. Then, when you access the VVOL, VASA Provider binds it to the PE on the same SVM and node.

Using PEs means that VVOL LUNs, unlike traditional LUNs, are not mapped. As a result, they do not contribute to the SCSI device limits on ESX hosts, but they do apply to the Data ONTAP FlexVol limits.

In an NFS environment, using PEs to access the VVOLs means that you do not need an NFS mount for each volume because they are not on exported and mounted volumes.

If you are using a block protocol, the PE is a very small LUN (approximately 4 MB) that is created in each volume. It is mapped to LUN IDs that start at 300. You must have a LIF on the SVM on the node, or VASA Provider does not create the PE.

The following graphic shows the relationship between the different components that make up a VVOL in a block environment. In the graphic, each VVOL has a PE that provides the access point to the VVOL.

If you are using an NFS protocol, the PE is the mount of the root volume of the SVM. You can have one PE per NFS LIF on the SVM. The PE determines the direct path used to bind each VVOL.

You can migrate traditional datastores to VVOLs using Storage vMotion.