HA with WLC5508 and licenses

Question

Hello.
We are currently running our wifi with a WLC5508 with a base license for 100 APs, a NCS and about 90 APs.
Now are wifi is growing and we will need more than 100 APs shortly. When I checked the prices I found that a new 5508 for 100 APs isn't that much more expensive than an add on license and it would be great to have some redundancy. If I use two 5508's with license for 100 APs, what will happen if one of them fails and all APs connect to the single 5008? Is there a way to use both licenses for a single 5508 in the case that one of them goes offline?
Bonus question: What happens when the NCS database grows to big for its disk space (running as virtual appliance)? Will it start to delete the oldest entries in the database or will it fail in some way?

Answer 1

Response for the Bonus Question:
If the NCS database grows too big for the disk space allocated, data will be deleted only according to the data retention settings under Administration>System Settings and will eventually crash if an additional virtual disk isn't added.  Keep in mind this warning starts popping up when the utilization on any of it's volumes goes above 60% so you probably have a little time. 
Check Administration> Appliance to see which volume is above that threshold.  It could actually be the localdisk volume causing the alert and not the database.
Adding additional disk space to Prime Infrastructure is as easy as doing an ncs stop, powering down the VM, adding a new virtual disk (NOT increasing the size of original disk), then powering the VM back on.
To add additional disk space to NCS the TAC has a disk grow script that has to be executed once the additional virtual disk is added or you'll never see the volume increase once you power the VM back on after adding the additional drive.