You should have some idea of your hardware requirements. This includes an estimate of your needs for system memory (RAM), along with processor power, networking needs, and storage requirements in terms of capacity and performance.

Go to your web browser and navigate to both the regular VMware vSphere Compatibility Guide at http://www.vmware.com/resources/compatibility/search.php and the VMware VSAN Compatibility Guide at http://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan.

The first link will take you to the standard VMware Compatibility Guide, and the second will take you to the VSAN sub-guide. By default, you will land on the system/server page, to help you select a server platform.

You should be on the VMware Compatibility Guide Systems/Server page.

You will need to filter your selection to restrict output to only the relevant results. To do this, carry out the following steps:

Example of the compatibility guide once filters are applied:

VSAN does also impose additional resource needs. Depending on the size of the disks you choose and how many, VSAN will consume additional compute and memory resources. If you typically run your systems close to the margins, in terms of compute/memory resources (or if you are planning to with your new cluster), consider specifying a modest amount of additional CPU and memory in the configuration. VSAN is capped at 10 percent resource utilization for CPU and memory as a maximum, so adding at least 10 percent to your assumed consumption should leave you with comfortable operating margins.

Additionally, VSAN requires a local boot device, either an SD card, or other low-performance solid-state memory, or a dedicated hard disk drive, or SSD. The boot device should be at least 16GB, in accordance with standard VMware recommendations. If your server configuration equals/exceeds 512 GB of system RAM, then you must use a hard disk drive or SSD as your boot device to ensure supportability, otherwise, a core dump cannot be written in the event of a system crash.

You should be on the VMware VSAN Compatibility Guide page.

The initial landing page for the VSAN Compatibility Guide will allow you to browse through VSAN Ready Node configurations. As we will be discussing the case of VSAN Ready Nodes later in this chapter, for now please click the "Build Your Own based on Certified Components" link from the main page of the VSAN Compatibility Guide:

Unlike the regular VMware Compatibility Guide, the VSAN-specific component guide is laid out as a branching tree that you can use to drill down to your desired configuration, after which time hardware choices will be displayed.

After making your selections, choose Update and View Results to get a list of hardware that matches your specifications.

Aside from simply ensuring that you select a supported storage controller, the VSAN-specific Compatibility Guide also provides you with additional detail that will be crucial to selecting your storage controller.

This view will tell you whether or not the controller supports the pass-through/JBOD mode and, vitally, it will tell you the controller's command queue depth. The controller's queue depth is a vital consideration. If each node is relatively small with one disk group, any queue depth above 256 commands is acceptable. If you have two disk groups, please consider 512 commands to be the minimum queue depth.

For large or high-performance configurations with several disk groups and extremely large capacities, and/or very high-performance SSDs, you should choose the highest queue depth you can. Standard controllers with maximum queue depths usually have around 1000 commands, like in the preceding example.

Queue depth can have a tremendous effect on the performance of streaming data. Opting for controllers and disks with deeper queues will provide better overall performance, particularly when VSAN is reconfiguring or resynchronizing data.

You should be on the VMware VSAN Compatibility Guide component page.

The Compatibility Guide for SSD is navigated in the same way as for the I/O controller.

Determining the size of your capacity-tier (magnetic or SSD) storage will directly affect the sizing decision for your cache-tier SSD. In general, the SSD should be 10 percent of the size of the magnetic disks in the underlying disk group, for example, if your disk group will consist of four 1.5 TB capacity-tier disks, you will have 6 TB of bulk storage. To accommodate this, the SSD should be about 600 GB. Alternatively, you may choose to opt for two disk groups consisting of three 1TB capacity disks each. In this case, each disk group should have a cache-tier SSD of 300GB. The ratio of cache-tier SSD to capacity-tier disks or SSDs should be approximately 1:10.

For additional guidance regarding how to appropriately size the VSAN capacity and cache tiers, please see the section Chapter 1 – VSAN Capacity Planning of Appendix A, Chapter-specific Expansions.

You should be on the VMware VSAN Compatibility Guide component page.

The Compatibility Guide for SSD is navigated in the same way as for the I/O controller

In general, SAS disks outperform SATA disks of equivalent capacities and/or rotational speeds because SAS drives use more robust recording technique, deeper queues or both. When cost is a concern, slower SAS drives (typically 7200 RPM; also called near-line SAS or NL-SAS) are usually built on cheaper SATA platforms but include enterprise-grade features like deeper command queues, error-correction, dual-channel connections and native SCSI support. Low-end SAS drives are typically better than high-end SATA drives despite the shared technology platform and costs are usually not significantly higher. NL-SAS is a great alternative to SATA for building out a cost-conscious capacity tier when HDD performance is a factor.

Before settling on a Cache + Capacity disk combination, please review the Chapter 1 – VSAN Capacity Planning section of Appendix A, Chapter-specific Expansions for a verbose description of the capacity expectations and recommended maximums to help you build your VSAN cluster to an appropriate scale.

You should be on the VMware Compatibility Guide IO Devices page.

Before settling on a networking standard, please take a look at a detailed description of the VSAN networking options and recommendations in the VSAN Network Considerations section of Appendix B, Additional VSAN Information.

You should be on the VMware VSAN Compatibility Guide landing page.

As with user-specified build-outs, please review the Chapter 1 – VSAN Capacity Planning section of Appendix A, Chapter-specific Expansions for a verbose description of the capacity expectations and recommended maximums, to help you select an appropriate VSAN Ready Node.