Here is a quick guide on how to choose good hardware for your VMware vSAN (Virtual SAN) implementation.

  1. DO the math before you start looking at the hardware. Make sure you know how much disk space (in Terabytes) and disk performance (in IOPS/bandwidth) you need. The disk space part is easier to calculate than the disk performance part, but they both need to be taken into consideration.
  2. DO learn how vSAN works when it comes to disk redundancy (Failures To Tolerate and Fault Tolerance Methods). This heavily affects the calculations for both space and performance above.
  3. DO use the hardware vendors’ vSAN Ready Nodes. They can be found at http://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan, and are available in different sizes and flavors.
  4. DON’T pick out your own hardware unless you really know what you’re doing. vSAN is highly dependent on high performing disk controllers and disks, and the vendors’ Ready Nodes are all thoroughly tested and validated, which makes them a good choice. If you still want to roll your own vSAN hardware, follow the following advice:

On this page, look up each part by part number, and make sure that they are on the list for the vSAN version you intend to run.

  • Make sure to read all the fine print. For example, the HPE SSD disk below is listed on the HCL, but it’s only recommended for the all-flash capacity tier, not any cache tier:

vsan-compat1

  • Another important factor for the controllers and disks is the queue depth. The controllers will have their queue depth listed on the HCL (see screenshot below), but the disks will not.

vsan-compat2

After implementation, it turned out that the HPE SATA SSD disks had a really low queue depth (10, instead of the expected 32 for a SATA drive). Make sure you ask the vendor or distributor about this before purchasing.

vsan-disk-queue-lenghts

  • Lastly, make sure you don’t upgrade the disk controller firmware or driver before checking that it’s on the HCL, and that it is validated and supported for the mode you intend to run (RAID0 or Pass-through). The controller below is only supported for RAID0 with the latest firmware+driver, so if we want to run Pass-through mode, we need to wait with the upgrade until the hardware vendor has validated the new version for Pass-trough:

vsan-compat3

 

I hope these tips will help you select good hardware and avoid ending up with a non-supported vSAN. Good luck!