June 05, 2015

vSphere Storage Terminologies - VASA


vSphere Storage APIs - Storage Awareness (VASA) is one of a family of APIs used by third-party hardware, software, and storage providers to develop components that enable storage arrays to expose the array’s capabilities, configurations, health and events to the vCenter Server.

The following are the Storage APIs in this family:
  • Storage APIs - Multipathing, also known as the Pluggable Storage Architecture (PSA)
  • Storage APIs - Array Integration, formerly known as VAAI
  • Storage APIs - Storage Awareness
  • Storage APIs - Data Protection
  • Storage APIs - Site Recovery Manager
You will find Storage APIs - Storage Awareness referred to by other names, e.g.
  • vStorage APIs for Storage Awareness, VASA
  • vSphere APIs for Storage Awareness
It enables more advanced out-of-band communication between storage arrays and the virtualization layer.

Storage APIs - Storage Awareness (VASA). This is an example of a vCenter Server-based API. It enables storage arrays to inform the vCenter Server about the array’s capabilities, configurations, health and events.

Storage array capabilities are exported to the vSphere APIs using VASA.

What is VASA?
  • vSphere Storage API - Storage Awareness  (formerly vSphere API for Storage Awareness, commonly known as VASA)
  • Introduced with vSphere 5.
  • A set of standardized VMware APIs that allow storage vendors to push storage-related information into vCenter database
  • Enables VMware vCenter Server to detect the capabilities of the storage array LUNs and their datastores.
  • Improves the visibility of Physical Storage infrastructure through vSphere client
vSphere Storage APIs - Storage Awareness requirements:
  • vCenter Server 5.0 (or later)
  • ESX/ESXi hosts version 4.0 (or later)
  • Compliant storage arrays (that supports Storage API - Storage Awareness)
A Storage (or VASA) Provider is a software component that is offered either by vSphere or by a third party. Third-party storage providers are also known as vendor providers. The third-party storage provider is typically installed on the storage side and acts as a storage awareness service in the vSphere environment.

vSphere (or built-in) storage providers typically run on the ESXi hosts and do not require registration. For example, the storage provider that supports Virtual SAN becomes registered automatically when you enable Virtual SAN.

The Storage Provider exposes three classes of information to vCenter Server:
  • Storage Topology: Lists physical storage array elements’ information
  • Storage Capabilities: Storage capabilities and the services offered by the storage array
  • Storage State: Health status of the storage array, including alarms and events for configuration changes
"The VASA provider enables communication between the vSphere stack — ESXi hosts, vCenter server, and the vSphere Web Client — on one side, and the storage system on the other. The VASA provider runs on the storage side and integrates with vSphere Storage Monitoring Service (SMS) to manage all aspects of Virtual Volumes storage."

The Vendor Provider is a third-party storage provider.

The vendor provider is made available by the storage vendor and installed on the storage array or on a management device.

Use the vSphere Compatibility Guide to verify which Vendor (or VASA) Providers are supported by your chosen storage array. E.g. below is a list of HP vendor providers supported at up to ESXi 5.5 U2:
Vendor Provider Benefits
  • Storage System capability, configuration, status is made visible to vCenter Server. This enables an "end-to-end" view of your infrastructure from the vCenter Server.
  • Storage Capabilities information can be used in system-defined entries for Storage Profiles
The VASA provider is supplied by VMware or the storage vendor. Storage (or VASA) providers can run anywhere, except vCenter Server. Typically, the third-party storage provider runs on either the storage array service processor or on a standalone host.

VASA Provider or Storage Provider:  A storage‐side software component that acts as a web service interface (API) for the vSphere environment.  It can either run in the array or outside the array.

"The VASA 2.0 specification describes the use of virtual volumes to provide ease of access and ease of manageability to each VM datastore. Each VMware Virtual Machine Disk (VMDK) is provisioned as a separate VVol within the storage system. A single point of access on the fabric is provisioned via a protocol endpoint from the host to the storage."

"With VASA, capabilities such as RAID level, thin or thick provisioned, device type (SSD, Fast Class, or Nearline) and replication state can now be made visible from within vCenter Server’s disk management interface. This allows vSphere administrators to select the appropriate disk for virtual machine placement based on its needs."

VASA and VAAI belong to a family of vSphere Storage APIs, use vendor providers to enhance several vSphere features and solutions. The two features work independently, and can coexist:

VASA (Storage APIs - Storage Awareness) collects configuration, capability and storage health information from storage arrays. One use-case is to build Storage Profiles based on array capabilities.
VAAI (Storage APIs - Array Integration) provides for hardware acceleration of certain storage operations, reducing CPU overhead on the host.


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