VMware vSphere Storage Appliance

One of the new products released with vSphere 5 is the vSphere Storage Appliance or VSA. In short VSA enables to create a high available storage system without the need for a Storage Area Network.
Small and medium businesses often do not have the budget for and the knowledge of shared storage. However they want to use availability features like VMware HA and vMotion. VSA brings this features from the enterprise to the SMB market.

VSA uses the local disks of vSphere 5 hosts to create a redundant disk array. VSA is a virtual machine (appliance ) which runs on every node in a cluster. A minimum of 2 and maximum of 3 nodes is supported. The VSA is very easy to install, 5 clicks and a few minutes. Only internal disks are supported for VSA, no SAN, NAS of JBOD. However direct attached storage will work but VMware does not support it untill it is fully tested and added to the HCL.

Currently a limited number of servers and controllers are listed on the Hardware Compatibility List (HCL) but that number will increase fast over the next few months.

The VSA is offered as a separate product or a la carte. Customers can purchase it together with any kit or edition of vSphere 5. It is sold per instance like vCenter Server. The VSA can be used on 2 or max 3 hosts.

The VSA is especially target at customers using the VMware vSphere Essentials Plus Kit. This kit offers both HA and vMotion.

VMware will offer a bundle of Essentials Plus + VSA for a discounted price. Untill December 31 a 40 % discount is effective on the listprice of the VSA when it is purchased with Essentials Plus . See the promo here

The listprice of the VSA will be $ 5995,-

VSA is managed using vCenter Server which has a VSA manager. There is a one-to-one relationship between vCenter Server and VSA. So you cannot manage/have more than one VSA per vCenter. That is a limitaion for enterprises having many branch offices with just local storage being centrally managed by a single vCenter Server instance. One-to many support wil be added in a future release.
Also on the vCenter Service the VSA Cluster Service is active. This makes sure there is no spilt brain scenario in a two node cluster when one cluster fails.

vCenter Server is required not to run on the VSA storage! This is because recovery would not be possible if vCenter itself is hit by a VSA storage failure (catch22).  

The VSA will present the disks as a NFS datastore. Only RAID10 is supported at the moment. Supported are 8 hard disks of the same model, capacity, and performance characteristics: 15000 RPM SAS 2 drives or  7500 RPM SATA drives. Less number than 8 harddrives is possible but performance will suffer from that. The servers requirements are: Two or three servers with homogenous hardware configuration. Each server needs 2 nics to support 4 port groups on each physical nic.

Across the nodes RAID1 is used. The local storage on a ESX node is divided in two. One half is used as primary storage, the other half as secondary. A primary on one VSA is mirrored to a secondary on another VSA. This mirroring across appliances is RAID1.

When a customer is using three servers with each 500 GB of local storage, the usable storage is 375 GB or 25% of the raw diskcapacity available. The sum is like:
raw storage 3 x 500 GB = 1500 GB
RAID 10 config = 750 GB
Mirroring between the VSA applianceds for resilience: 375 GB of useable storage.

When three nodes are use, one node can fail and storage is still available. If two of the three nodes fail, there is no VSA anymore.

If a customer grows beyond the VSA and buys shared storage, using storage vMotion virtual machines can easily and without downtime migrate to the SAN.

Datastores on VSA cannot dynamically be expanded if more disks are added. This will be a feature of a next release.  

The VSA has been qualified with Site Recovery Manager feature of Host Based Replication.

This video shows the install of the vSphere Storage Appliance

See the vSphere Storage Appliance FAQ on VMware.com

VMware published a document titled Performance of VSA in VMware vSphere® 5 It shows the results of benchmarks performed on VSA and explains best practices.

The presentation on VSA given by VMware can be downloaded here: new_vspherestorageappliance_customer_presentation

The 40% discount offering can be seen here.

The VSA brochure can be seen here 

The VSA whitepaper can be seen here.

A blog on VSA here

Justin’s IT blog has a good posting about the VSA here.

Alternatives are here like Stormagic  Virtual SAN (SvSAN) software. It has the same functionality of the VMware Storage Appliance: creating high available storage out of local attached harddisks. Indication of costs: It’s $995 per ESX server on the 2TB version of SvSAN. If more capacity is needed the costs increases. See for an overview of all option here.

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About Marcel van den Berg
I am a technical consultant with a strong focus on server virtualization, desktop virtualization, cloud computing and business continuity/disaster recovery.

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