The rules are different with SSD drives versus mechanical HDD’s. SSD drives have a latency in microseconds where as mechanical drives have a latency in milliseconds. This means SSD drives can read and write far more files in a given time segment than mechanical drives. If you have an SSD then cache and media files can go there without issue. You can also include cache files easily with an OS drive on an SSD. Mechanical drives are where the separate drive philosophy really developed from. Although you can run media and cache from the same drive provided the drives and interface ie e-sata, USB3 or TB are fast enough. Firewire and USb2 would not be
Eric-ADK
Tech Manager