I've been using Sonar for a few years now, I finally have Platinum, and upgrades and everything. The laptop I use has an SSD (C) as the system drive, it's small and has 120gb. I have a second internal (D) drive with 1tb of storage that I keep all of my applications on. 
 
SONAR refuses to install on the D drive. I've changed the settings on the computer, the CCC paths, the registry, everything. The closest I got was everything was on the D drive except it wasn't finding 3 of my core plugins. I'm getting frustrated. It's slowing my computer down, and I've probably spent a total of 4-5 weeks trying to fix it. Countless reinstalls. 
 
How do I get SONAR to fully understand I want it on my D drive and not my C drive.

Hi Vermillion221:
I just want to give you a small advice only trying to help. If I didnt misunderstood your C drive is a 128 SSD and your D drive is an internal  1Tb normal hard disk and that is fine. But if any application should reside on SSD is SONAR because SSD speed helps a lot for not having audio cut outs. So your system files, your SONAR application and your working cwp projects should reside on your SSD for better performance. Once you have finished working with them then you can store the final results in the 1Tb normal disk.
Few months ago I had a 4 years old laptop with windows 10, 4Gb memory, 256Gb internal normal hard disk, SONAR Platinum. When I used 4 software instruments I was starting to have audio cut outs that I couldnt avoid with buffer and Asio settings. The problem was disk speed. Then I aquire a new 500Gb SSD and 4 Gbs of additional memory and replace the internal 2.5 normal hard disk with the new SSD all the problems finished and the working speed increased sustancially.
I understand your SSD drive is small, but 128Gb hould be enough for the system and Sonar. If you have to move applications out move other applications nor Sonar.
 
Regards
Carlos

I have a 120 GB C drive on my main DAW and by managing the sample libraries you can have Sonar and all your software on the C drive no problem. Mine is sitting at 45 GB and I have a lot of music apps on it. 
What I do is let the Programs install everything to C drive first, then I move the samples  and tell Sonar where they went. 
All my Project folders are on a second DATA drive along with the Libraries. No data is stored on C drive other than a few pictures and whatnot
 
One thing to keep an eye on is the CCC download folder which you will want to move to the D drive once finished. It can grow to 20 GB or more. It's found in C/Program data/cakewalk/Command center
But many people use 120 GB C drives without issue. 

So it's possible to have the application on the C drive, but is it possible to have Rapture, Dimension and all the beefy MIDI libraries on the D drive? Because I think that is my biggest issue. I also am not sure how to tell SONAR where they went.
 
I've had everything on the D drive before, I was so close to getting all working the way I wanted it to, but it couldn't find TH3, my most used plugin. 
 
I just want to find the best way I can optimize my storage options. 

Vermillion221
So it's possible to have the application on the C drive, but is it possible to have Rapture, Dimension and all the beefy MIDI libraries on the D drive?

Absolutely yes it is possible.
 
Your asking for problems by trying to install Sonar on a separate external HD.
Install Sonar on main SSD C:\ and Samples on external HD

Do you have a step by step for separating the installation? I've been at this too long and tried too many things to think about it logically. 

where are installing from ? Command center or verbose ?
http://forum.cakewalk.com/Need-help-with-Sonar-installation-pathways-m3547449.aspx

In the CCC, Click on the "Gear" icon in the upper right of the panel then click the Path tab. 
You can make changes there.

Do you have everything installed on C:?
If not, what is the status of the installation?
 
It is just as easy to move stuff as it is to reinstall and if moved properly you will never have to worry when added new content to the synths. The same method works for the Command Center and avoid having the setting change unexpectedly for you. I will be glad to provide those instructions or if you want to perform a clean install of everything Cakewalk I can provide those instruction too. The knowledge base can help with the latter but there is an issue with one of the steps.
 

Currently, everything is uninstalled and I was planning on installing everything from CCC.