Hello,
Note there is also memory consumption for ESXi (already accounted for if you are running on this) and additional memory overhead per vSAN disk-group and varying depending if Hybrid or AF, this outlines these:
kb.vmware.com/kb/2113954
Sure, you *could* likely set-up a vSAN using an onboard controller (I tried to find specs of what comes on a 5028D-TN4T but none found easily) but this would likely not function very well due to the low Queue Depth typically capable on these types of devices, pretty much nullifying the benefit of All-Flash and even vSAN at all really.
It would likely end up being a bad bottleneck, depping covered this topic long ago:
yellow-bricks.com/2014/06/09/queue-depth-matters
For a comparison of what should be expected minimum Queue Depth you can refer to even the lowest-capacity/specs ready-node require minimum >256 Queue Depth, which is the minimum requirement for vSAN:
partnerweb.vmware.com/programs/vsan/Virtual_SAN_Hardware_Quick_Start_Guide.pdf
vmware.com/resources/compatibility/vsan_profile.html
Bob
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