VMware vSAN - A closer Look [Part 1 - Introducing and licensing]

Recently I’ve been designing solutions based on VMware vSAN for various infrastructure refresh projects across our customer base. Whilst many of our customers have a good high-level understanding of vSAN this series of blog posts will cover some of the concepts in further detail and hopefully help answer some of the typical questions I get asked.

This post is the first of a seven-part series. Over the coming weeks the links below will be updated as new parts are released.

  • Part 1 – Introduction and licensing
  • Part 2 – Architecture and Hardware
  • Part 3 – Data Availability
  • Part 4 – Fault Domains and Stretched Clusters
  • Part 5 – Failure Events
  • Part 6 - Compression and Deduplication
  • Part 7 – Monitoring and Reporting

What is vSAN?

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vSAN is a distributed object based storage from VMware and has been around since 2014. The initial GA release was vSAN 5.5 and over the last few years there have been several major updates to the product with each one bringing many new features and enhancements. As of today (September 2017) the current version is v6.6.1. The minimum number of hosts required for vSAN cluster is 3 and can scale to a maximum of 64 hosts. For very small deployments such as branch offices it is possible to have 2 hosts plus a remote witness host. There are some considerations around data availability during maintenance with the minimum number of nodes but more on this later. vSAN can easily scale upwards by adding additional hosts, or scale outwards by adding new devices to an existing host. This is completely non-disruptive and means performance and capacity can be scaled independently.

One common question is what needs to be installed or deployed to get vSAN working. Well the answer is quite simple – nothing! vSAN is fully integrated into vSphere and leverages local storage from clustered hosts which is presented as a single datastore. There are no appliances to deploy or any vibs to push out to hosts and vSAN typically consumes less than 10% of compute resources per host. Enabling vSAN can be completed with a few clicks of the mouse.

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Features and Licensing

Traditional block and file based storage arrays typically offer many enterprise grade features such as thin provisioning, snapshots, replication, compression, deduplication, encryption and more. When discussing replacing traditional storage arrays with a software defined storage solution such as vSAN there is sometimes a concern that these features may not be available to use. Well the good news is vSAN supports all the above plus more. As with most VMware products there are several licensing options available depending on the features you require. The three choices are standard, advanced and enterprise with each being licensed on per CPU socket model. For ROBO there are two choices – standard or advanced which are available in 25 VM packs. Similar to the vSphere licensing model, you can split a pack of licensing across multiple locations, however a single site can have no more than 25 virtual machines running. I’ve included the table below from the latest vSphere licensing guide which gives a comparison of the features available with each license type.

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Note: RAID5/6 Erasure Encoding, Deduplication and Compression features are only supported on an All-Flash vSAN configuration.

Part two of this series will cover the architecture of vSAN and what needs to be considered when selecting a hardware platform to run vSAN.