What I currently have is an iMac with a Fusion Drive, A 8TB External Drive for all my photography and a 8TB External Drive for all my videography. Both are USB3 and I believe they are WD 5,400 rpm RED NAS drives.
Premiere is on the Fusion Drive
I keep the actual project files (I'm working on) on the same Fusion Drive
Additional video files are on the Video Drive
All my Scratch Settings are pointing to the Photo Drive The Photo Drive is the least used drive while I am editing.
Today I received an External 512GB SSD drive and I am wondering of the 4 different elements, what would be the best configuration?
It would not be wise to try to play multiple layers of 4K Red One R3D files or 4K Pro Res files of a mechanical hard drive. On the other hand 4K H.264 can be played from a mechanical hard drvie. The video below should help answer your question. That being said you might need to empty the media cahce files from time to time.