HI Mick,  You seem to confuse SDC with SDS - SDC is ScaleIO Data Client, it doesn't contribute any storage to SIO pools - that's the job of SDS (ScaleIO Data Servers).  Yes, you can leave it just there, especially if you plan to use it in the future - SDC installation requires a reboot (or two) of ESXi, so it's better to leave it running. It's actually mentioned in the documentation - better to install SDCs on all ESXi that can potentially be used in the future during the maintenance/installation window rather than doing it at later stage (due to reboots).  I don't think there's any trivial way of disconnecting an SDC in ESXi environment - in Linux or Windows you could try to stop the server, in ESXi you would need to either remove the VIB completely or change its parameters so the MDM IPs are not set - but I would recommend you to leave them as they are.  Hope that helps! Pawel
HI i have a host with the sdc installed but its not added to the scaleio cluster so its not contributing storage or has any volumes mapped. It is listed however in the sdc's in the scaleioGUI - i try and remove it but it says it needs to be disconnected first - how do i do this ? i dont see any command line option for this either  Also - this host will actually be going back into the scaleio cluster soon - is it better just to leave the sdc connected as it is and add it to the scaleio system using the gui wizard ? 
disconnect sdc