VMware Virtual SAN: The great Debate….

Over the course of the past few weeks, since VMware’s Virtual SAN has GA’d, we are seeing an abundance of SAN VS VSAN blog posts. I”m not going to get into what VSAN is, if you’re reading this article, more than likely, you already know.  If not, go here to get all the info you need:  VMware VSAN .

For some reason, we continue to see blogs that compare Traditional SAN vs VSAN WITHOUT representing the entire case to the public. This is completely biased, if you ask me.  Writing articles without including all the facts, usually results in a favorable opinion to the original authors argument.  It’s no secret that not laying out all the facts is just another type of “misinformation” technique, heck the news does it all the time but sometimes, people provide opinions without truly knowing ALL the facts.  Either way, it’s a disservice to the readers so let’s lay out some of the facts I see missing when comparing traditional SAN vs VMware’s Virtual SAN.

1. VMware Virtual SAN is built in the VMware Kernel.  The benefits are a low latency storage access, which, for VMware workloads is the top performance characteristic next to IOPS that needs to be addressed.

2. VMware Virtual SAN provides Operational Efficiency by leveraging a single DataStore, little to no MGMT for provisioning..etc AND Policy Based Management at the Virtual Machine Level.  This is usually not called out in SAN vs VSAN articles.  The question is, how to place a monetary value to those efficiencies and that’s the tough part.  Having said that, it should certainly be called out when making these comparisons.

3. VSAN is a Hyper-Converged solution, period.  Compute as well as storage is included in one “box.”  Therefore, we need to make sure that when doing this comparison, you are only including the Disk Controller, Disks, & VSAN Licensing, not the entire Node cost.  Traditional SAN’s do not include compute for VM workloads.  The Compute is purpose built, for storage level tasks and management, and in reality, when you think about it VSAN is very efficient when compared to the traditional SAN SP model.

4. There are two ways to build a VMware Virtual SAN solution:(Credit for latest information to Wade Holmes..thanks Wade)

  •  The Virtual SAN Ready Node program is different from existing VMware Compatibility Guide (VCG) programs; it is a certified combination of components rather than an individual product listing. The entry point into these listings is Virtual SAN Ready Node which will certify the Server, I/O, HDD and SSD combination. Once the Ready Node is assembled using certified components, Virtual SAN Ready Node tests can be run, and results submitted to VMware. After a successful review of the results, the complete Virtual SAN Ready Node will be listed on the VMware Compatibility Guide. The partner can then proceed to Virtual SAN Ready System listings, which will expand on the Ready Node certification.
  • Virtual SAN Ready System focuses on 4 different categories, Entry, Capacity, Performance, and Balanced. Each listing will expand on specific Server, CPUs, Memory, I/O, HDD, and SSD components that map to the Ready System classification. Partners will work with VMware on defining these systems and assist with the listing. Ready System help customers to quickly find the solution that best suites their need.

To break this down, simply you can buy a prebuilt validated Node/System from a VMware VSAN Ready Node/Ready System Partner such as Dell, Cisco, and Supermicro, or you can build your own Hyper-Converged solution using the VSAN Compatibility guide.  Talk about choice!  We all know that there are customers that stick to what they love, and this gives them that choice.

Additional information can be found here: Virtual SAN HCL Help

5. You must assess your environment/workloads/future growth etc the same way you would size for any Traditional SAN.   You have a set of workloads that need a certain performance/capacity level and a use case, and you as the customer, or a good partner will size this appropriately.   Duncan Epping over at Yellow Bricks has provided a great VSAN Sizing tool to assist in this process located here: VMware Virtual SAN Sizing Tool .

6. VSAN is NOT for all environments but has several use cases such as VDI, DR, Production at scale, Scale out friendly environments etc.  It’s not a one size fits all solution, yet.

7. Pricing argument per TB.  Chris Wahl called this out on Twitter yesterday here:   “I don’t get this pricing nonsense. A customer will have requirements, use case & $$$ will either fit or it wont”

I couldn’t have said it better.  Chris hits the nail on the head yet again!

As you can see there is much more to VSAN than what’s posted in the SAN vs VSAN articles in the blogasphere, and of course I only scratch the surface.  You can find much more information from the experts like Cormac Hogan and Duncan Epping who have written several posts about VSAN’s capabilities etc.  I encourage you to read their articles.

I’m all for playing the “Devils Advocate” when it comes to new products.  As technologists, engineers, architects, we have to for the sake of our customer and our reputation, but we need to make sure that all the facts are laid out on the table when doing comparisons.  We need to do it better than the News Orgs that report only bits an pieces of information, all the facts need to be provided so people can make informed decisions.


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