This is just my list of prerequisites for a VSAN upgrade.  Most of these items are applicable to a new install as well but more focused on a upgrade.

Please feel free to provide feedback and would to add to my list with your experiences.

Prerequisites:

• The VSAN on-disk metadata upgrade is equivalent to doing a SAN array firmware upgrade and therefore requires a good backup and recovery strategy to be in place before we can proceed.

• Enough resources => 3 node cluster!
• If 3 or less node cluster then unable to evacuate the disk groups
• Run RVC command:  > vsan.ondisk_upgrade –allow-reduced-redundancy
• Requirement of 6 GB of RAM inside a host with 6.0U2 running VSAN. (for lab environment)
• Each host should contain a minimum of 32 GB of memory to accommodate for the maximum number of 5 disk groups and maximum number of 7 capacity devices per disk group.
• Verify no stranded objects on VSAN datastores before disk format upgrade.
• VM swap object left behind
• https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2144881
• Locked CBT file
• https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2144882
• Broken snapshot disk chain
• https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004232
• Run python SCRIPT to find and fix stranded objects.
• 2144881_VsanRealign
• https://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2144881
• Verify the storage controller on the host is compatible
• Verify the storage controller is set to pass-through or HBA mode for RAID.
• Verify the storage controller has caching disabled.
• Open VMWARE HCL and verify that your firmware is up date for all server components.
• https://www.vmware.com/resources/compatibility/search.php?deviceCategory=vsan
• Persistent logging folder for VSAN trace file and rest (USB or SD-card ESXi install)
• http://cormachogan.com/2015/02/24/vsan-considerations-when-booting-from-usbsd/
• http://cormachogan.com/2015/08/14/handling-vsan-trace-files-when-esxi-boots-from-a-flash-device/
• I do recommend you install vRealize Log insight for syslog collection, after all its free for up to 25 OSI)
• Networking:
• Hybrid requires at least 1 x 1GB connection
• Flash requires at least 1 x 10GB connection
• Layer 2 multicast must be enabled on the physical switch
• Each ESXi host in the cluster must have a vmkernel port