NetFlow data is not available from servers or storage. It is a feature found mostly on Cisco routers although some switches support it as well.
There are other ways of getting traffic\bandwidth information about your servers and storage. One thing to check is SolarWinds NPM which uses SNMP to query the servers\storage and from this you can get things like Ethernet port utilization. If you need more detail then you also have the option of SPAN ports on your switches