I do agree: check out VMS bandwitdh max input and outputs... ( not only inputs) because video wall and any client outputs using basic high resolution streams could saturate the server CPU as well. Multicast settings as well (does explain why we can't put too many camera per server with Genetec)
That's why also VMS using second or third low streams are recommended instead
then max Read / Write in term of bandwitdth trhoughput on the NAS, not only fps writting
Keep in mind a 8 cameras synchronized reading in fast speed can take 8x 30 Mbits= 240 mbits ! only for one operator working on a search.
VMS Bandwith Input: (but also throughtput to the NAS) so use same for NAS output
8 Megapixels : 24x8*=Mpixels outdoor with moves & lights changes= 192 for the REC only ...
10 Mpixels cameras : 16x10* Mpixels outdoor with moves & lights changes= +/- 160Mb
(*may be more at night) TOTAL: +/- 352 Mb/s input and 352 Mb/s output to NAS
If your server is doing motion PTZ tours, motion detect, or analytic add some CPU, used by pre/post alarms and analytic engines
+ any optionnal display streams : for example, VGA for multiple displays or QVGA for SmartPhones
So CPU should stand 700 Mb instant treatment minimum.. not easy on a single server
And during replay .. could reach 940 Mb ....(in that example)
Port miroring feature on Level2+ switchs can help to see whats coming in and out from the VMS during normal usage. Night time is always the best to do the stress test, with synchronized replay which probably kill most systems