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Virtual SAN 101

What Is Virtual SAN?

Over the past decade, VMware has revolutionized server virtualization, and more recently, desktop and network virtualization. Welcome Virtual SAN (VSAN) to the virtualization product family, VMware’s foray into the storage virtualization market!

VSAN provides storage space for virtual disks that hold the data needed to run VMs. It is built directly into vSphere, VMware’s virtualization OS, which means that administrators will feel right at home when deploying and managing the software-defined storage solution.

VSAN pools all of your internal storage, hard drives and / or solid state drives, which are used to store virtual disks. Before VSAN, administrators had to manage storage separately, allocating resources through LUNs (logical unit numbers) or volumes. With VSAN, the approach is completely opposite; when you create a VM, you specify your requirements from a storage standpoint, implement policies (capacity, performance, availability), and you’re done.

Why Use Virtual SAN?

The common phrase at VMworld 2014 was “if you know vSphere, you know VSAN.” VMware has made it completely seamless to deploy VSAN within vSphere with a two-click install. Upon deployment completion, the administrator has a single pane of glass to monitor and manage all policies, VMs, etc.

Your storage needs are granular and linear meaning they scale as you scale. The storage itself is accelerated by the flash found in your hardware configuration. Flash-based devices are used to build the flash tier in the form of a read cache and write buffer which dramatically improve the performance of each of your virtual machines.

Lower Total Cost of Ownership
Due to the simplicity of the solution, there is no additional training or expertise required by your administrators. What's most exciting from a cost perspective? VSAN is a "grow as you go" pricing model meaning that you only need to increase disk storage as your data storage itself grows. This eliminates the need for a large upfront investment.

Who Is a Good Candidate for Virtual SAN?

VMware IT Shops
VSAN is for the VMware centric IT shop that’s looking for a simpler way to provide storage. It’s also a solid solution for a shop without a storage specialist; the server group can now easily deploy storage without purchasing or understanding additional technology.

Ideal Hardware
In terms of technology, an ideal VSAN candidate will be deploying at least three servers and understand the potential I/O drawbacks of the solution.

Initial Capital Expenditure
VSAN is for businesses that can afford $2,495 per server processor, or $50 per desktop user. This is quite pricey for continually flat year-on-year IT budgets. There is also additional capital outlay in 10GB networks to ensure high interconnectedness of the network, as well as doubled HDD or SSD investment to optimally replicate the datastores. Many SMB IT leaders at VMworld 2014 shared, “this is something that I’ll be looking at in 3 years.”