You can easily find out if NCM is installed.
Login to the ESX host and run the command below:
(I'm not using the latest version here)
[root@esx1:~] esxcli software vib list | grep nimble
nimble-ncs 2.3.1-600006 Nimble VMwareAccepted 2015-06-27
nimble-psp 2.3.1-600006 Nimble VMwareAccepted 2015-06-27
If NCM is not installed then you probably didn't adjust your existing baselines or didn't create a new one for NCM.
I SSH into each host and issued this command
esxcli software vib install -d http://update.nimblestorage.com/esx6/ncm
When I look at what was installed, it does show version 2.3
What command should I use to install version 3?
Do I need to uninstall version 2.3 before installing version 3?
Why didn't Nimble's documentation mention this!!!!!
NCM 2.3 is the latest GA release - so running the command will pull down and install that code.
NCM 3 is tied to NimbleOS 3 which is currently RC status - but we expect this to change fairly shortly. So if you have scope, it may serve you well to remove NCM 2.3 and install NCM 3. Any VIB removal requires a VMware reboot. Or you could do it in the future should you wish.
NImble documentation is published for each release. The best thing to do is to speak with your local Nimble SE or give support a call, who can provide you guidance.