VMware VSAN : Setting Up the VMware VSAN

VMware VSAN : Setting Up the VMware VSAN
As you may aware VMware VSAN is a new software-defined storage tier for VMware vSphere which is bringing the benefits of the Software Defined Datacenter (SDDC) to Storage. Using a VMware Clustered ESXi Hosts SSDs and HDDs it creates a flash-optimized high resilient shared Datastore for the ESXi Hosts.
Here I’m not going to discuss about the benefits and the new features of the VSAN and I will discuss those things in a different post in my blog. Firstly, I would like to give you the overall view of the VSAN in a graphical way which you can easily understand the picture behind the scene. Image courtesy goes to the VMware Developer Center.



VSAN is natively configured with vSphere and you can easily configure in few mouse clicks. I’m going to show the clear steps which I followed to build my Virtual SAN which I created with three ESXi nodes.

Before I move in to the implementation I would like to mention the requirements of the VSAN implementation. This is the VMware recommended requirement for the VSAN

  • At this moment VMware vSphere 6.0 U2 is recommended with vsan erasure coding (RAID-5/6) (My configuration is based on vSphere 5.5)
  • Minimum of three ESXi hosts
  • 6GB of Minimum memory for configuration and 32 GB of minimum recommended memory
  • In production if ESXi hosts exceeding the 512 GB memory dedicated magnetic disk required for the ESXi hypervisor installation, SD and USB devices are not supported.
  • Certified Disk controller , Pass-through/JBOD needs to be supported otherwise single disk needs to be configured as RAID-0
  • At least one certified flash disk for caching
  • Dedicated 1 GbE NIC or shared 10 GbE, VSAN traffic can be shared with Management, vMotion, Fault Tolerance if it is 10 GbE
  • Multicast should be enabled in the VSAN network (L2 or L3)

Setting up the virtual network for the VSAN

First of all I’m going to setup my Virtual networks for the VSAN traffic and I’m using Standard switches with two vmnics. There is no difference of creating a Standard Switch in this configuration and you need to get familiar with the vSphere web client for the VSAN configuration and you can only do this configuration using the vSphere web client. But for a complete article I would like to provide all the steps to get start with VMware VSAN.
Select one of your ESXi host and navigate to Manage and Networking section, under Virtual switches click on “Add host Networking” create your virtual switch for the VSAN.


Select the connection type as the “VMkernel Network Adapter” and click “Next”

I’m going to create a new “Standard Switch” for this VSAN traffic and select “New Standard Switch” and click “Next”

Add two “vmnics” in the next step by clicking the green plus sign under “Assigned Adapters” and click “Next” to continue.

Add a network label and enable the Virtual SAN Traffic in the next step. Click Next to continue

Add an IP Address for your VMKernel and click “Next” to continue.

Review the configuration and Click finish to complete the VSAN standard switch configuration.

My Standard Switch Configuration is like this

Note: You can use the Distributed Switch for this Configuration and You can enable the SAN traffic to flow through the Distributed Switch. As I mentioned before there is no difference of the Network configuration other than allowing the VSAN traffic in your vMKernel. There is a good thing , I believe that you know there is an Enterprise Plus license requirement for the VDS and VSAN license allows you to create a VDS for your VSAN Distributed Switch.

Create the VSAN Cluster

Now what I’m going to do is create a VMware Cluster and turn on the VSAN feature to create the VSAN.
Right-click on your Datacenter and select “New Cluster…”
Provide a cluster name as usual and check the VSAN option and select the disk addition methods to claim your disks for the VSAN.
There are two options to claim disks for the VSAN :
  • Automatic – It will claim all the empty disks in your ESXi hosts for your VSAN configuration
  • Manual – You have to manually add any new disk for your VSAN

I’m using manual mode for my VSAN configuration

Note: You have to have a separate VMware license for this and 60 days of evaluation licensing will be selected by default. This VSAN feature is not covered under your vCenter License.

Now drag and drop your ESXi host to the created cluster

You can see the resource and disk utilization and the disk management under the cluster management Section


Creating Disks Groups for the VSAN

We have successfully created the VMware VSAN and now it is time to create the disks groups for the VSAN. When we are creating the VSAN it contains either a combination of Magnetic disks and Flash drives (Hybrid VSAN Configuration) or all Flash drives (All-flash configuration).

  • Hybrid VSAN Configuration – one flash device and one or more magnetic divice are configured as a disk group. Normally, one disk group can have up to 7 magnetic disks. Flash devices serve as “read-and-write” cache for the Virtual SAN datastore while magnetic disks serve to create the capacity. By default VSAN use 70% of it’s flash capacity to read and 30% of flash capacity to the write cache. However new features which are available in 6.2 like “De-duplication and Compression” is not available in Hybrid VSAN Configuration.
  • All-flash Configuration – Flash devices in the cache tier is only used for the write caching and there is no read caching as the read performance of the capacity devices are more than sufficient for the Virtual SAN.

Go to disks management and click on “Claim disks” to claim your Disks for the VSAN

Select the disks which you are going to add to your VSAN datastore, you need to select at least one SSD disks for the Configuration

It will perform a disk validation while you are adding the disks and will throw an error if you haven’t select the correct combination of the disks.

Once you are correctly added the disks to your VSAN datastore it will create the “vsanDatastore” for you and you can see it under your datastores.

Possible Errors when you are adding disks and creating the vsanDatastore

I encountered with the below error when I added more than one Magnetic disks to my VSAN and it allows only 1 magnetic disks for a Host with 4GB RAM. Error is pretty straight forward and you can easily understand the issue. Once I selected one SSD and One Magnetic Disk I was able to create the vsanDatastore without an issue.



Also there was an error occurred saying “Unable to create LSOM file system for VSAN disk…” and I found that this can be occurred due to the time difference of the Hosts and the vCenter. I have corrected this and it was not able to fix the issue. Finally, I had to increase the RAM capacity of the Hosts which error occurred and it fixed the issue.


It became a lengthier post and hope you enjoyed and found some value in this. Thanks for reading my post.

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2 responses

  1. meghanasmiley03 Avatar

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  2. Aruna Lakmal Avatar

    Glad to hear you have bookmarked my blog. Keep reading my posts and you can learn more about VMware. Thank you for your comment.


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