Customers vSAN

Ten Things You Need To Know About VMware vSAN

Updated June 21, 2017


Here’s the headline: VMware vSAN fundamentally changes the way vSphere administrators do storage. It’s a new world.

While there’s a ton of good material out there, we thought we’d boil things down to the bare essentials for all you busy IT professionals.

Here’s what you need to know:

1. vSAN eliminates the need for an external storage array

vSAN pools flash and/or disks that live in servers to create a single, shared datastore for a cluster. That means there’s no need for external storage, a storage network or a storage administrator. Although an external array isn’t needed with vSAN, it certainly works well alongside them.  Admins can easily create policies that place workloads on vSAN, external arrays — or easily move them back and forth with Storage vMotion.


2. vSAN is designed for vSphere administrators

Every aspect of vSAN is designed to be as simple as possible for a busy vSphere administrator. For example, there is no “storage console” or plug-in, because all the workflows have been seamlessly integrated into vCenter’s web client. The simple premise is that if you know vSphere you’ll know vSAN in no time. This works great for vSphere administrators that can manage both the vSphere environment and the storage environment for their virtual machines from the same UI, or even to IT administrators that wear multiple hats. The workflows are very intuitive, which means that vSAN can be also easily managed by storage administrators that would like to keep control of all storage resources in their environment.


3. vSAN uses policies to define storage attributes

With vSAN, the vSphere administrator defines policies that include things like protection levels, striping, thin provisioning, Quality of Service (IOPS limits), erasure coding etc. and simply refers to an existing policy when provisioning a new VM.

vSAN dynamically carves the requested storage from the single datastore — there is no need to pre-allocate different protection and performance levels as with a typical external storage array.

Every VM (and its VMDK) could potentially have a different policy, if you wanted.  For example, you could have some VMs be able to tolerate one failure, some tolerate two failures, and some that can’t tolerate any failure — all intermixed within the same data store. You can have some VMs use space efficient ways to protect data (e.g. RAID-5 or RAID-6) and some VMs use more performance oriented approach for the same purpose (e.g. RAID-1), with just a few clicks in the VM policy interface.

Even better, when you change a given policy, vSAN automatically makes the changes on the back end. This approach is much simpler and less wasteful that the traditional way of doing things.


4. vSAN is designed to be the best storage for your VMs

Each VM communicates with vSAN using an internal protocol that’s simpler and faster than a standard storage protocol.

If you want to expose vSAN capacity externally via NFS, there are good partner solutions available.


5. vSAN can be amazingly fast

Depending on the hardware you run it on, vSAN can deliver surprisingly high levels of performance. It’s a real eye-opener. Critical data paths are optimized, and there’s no need to run IOs through an external array’s controller.

All-flash vSAN can deliver stupendous performance very cost-effectively. Performance scales linearly as more servers are added to the cluster. Individual servers can support multiple disk groups, each of which adds to vSAN’s performance. More hardware = more capacity and more speed. vSAN can also optimize all flash capacity usage using deduplication and compression, with very minimal impact on performance.

Better yet, as server hardware gets faster and cheaper, vSAN gets faster and cheaper as well – a major win for the customer!


6. vSAN can have very attractive economics

Because vSAN runs on standard server hardware, components are very cost-effective to acquire. Be sure to check the vSAN Compatibility Guide though!

vSAN isn’t priced based on capacity as is the case with most external storage arrays. The more storage you put behind your cluster, the more cost-effective vSAN can be. Add the new space efficiency features into the equation and you’ll get the best bang for your buck for all your vSphere storage needs.


7. vSAN is incredibly robust

Almost every time someone tests vSAN, they give the availability features a thorough workout. They fail drives, controllers, servers, networks — the works! That’s great — but they discover what we already knew — vSAN has a very resilient design. See vSAN Performance Testing Done by

The new Health Check Service also gives administrators a quick view of their vSAN hardware and network — in addition to making sure an unsupported driver hasn’t inadvertently slipped in. The new monitoring dashboards will give you an accurate picture of how Virtual SAN uses the underlying capacity, and what is the current performance load in your vSAN cluster.

Even when disaster strikes — a total network partition, or a power fail — it’s designed to never lose data. And don’t let any array vendor try and tell you otherwise


8.  vSAN is dead simple — really

While some people enjoy getting really deep into vSAN’s functionality, most folks have other things to do. Our users tell us that they love that vSAN doesn’t demand their attention all the time. “Set and forget” gets mentioned a lot. Read the Top 4 Benefits of vSAN As Told by Customers. Also, check out some of vSAN Case Studies from some of our 8000+ customers.

The best part?

There’s no need to learn about storage arrays, or be a storage expert.

Read 7 Reasons Why vSAN is Radically Simple.


9. vSAN upgrades are easy

Need more capacity or performance? Just add more hardware to your existing cluster.

Moving to a new cluster? Take your licenses with you.

Software updates are easy as well. Since vSAN is part of vSphere, upgrades work the same way.


10. vSAN and Horizon are a match made in heaven

While vSAN does well on all sorts of datacenter workloads, when paired with Horizon an extra layer of goodness emerges.

In addition to vSAN’s clear performance and cost advantages, vSAN understands Horizon’s desktop pools and configures itself appropriately. There’s no need to go back and forth with the storage team — the Horizon administrator is completely in control of the environment.

If you’re using linked clones, capacity requirements are so modest that all-flash becomes very attractive. If you still prefer full clones, just turn on vSAN’s deduplication and compression to get up to 7x space savings in such scenario. If your desktops aren’t persistent, you can consider using a failures-to-tolerate setting of zero, which makes vSAN even more cost-effective.

Compared to an external array, the differences are night and day.

Want To Know More?

Our vSAN Hands-on Lab (HoL) can give you a great feel for the product quickly and easily.

To find out where  vSAN would fit in your environment, Sign up for a vSAN Assessment.

If you’d like to look at hardware configurations, check out our list of pre-certified vSAN ReadyNodes.

And if you’d like to do a TCO calculation for your environment, check out this nifty tool.

The rest of our handy resources can be found right here.

And now you know what you need to know!


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