External hard drive to make AE faster / more efficient?

Memory: did you mean storage?

By @Syntax_One

No, by memory I meant what’s generally called RAM, which Apple calls Unified Memory for its Apple Silicon Macs. I only mentioned RAM as an analogy, because the performance benefits of more RAM are the same as with the media cache: Once you have enough, adding more doesn‘t make the computer go any faster, because it never was speeding up the computer, it was only addressing a bottleneck that was preventing optimal performance.

If I suggest they use their external drive for temporary files, is this where they have to configure everything?

By @Syntax_One

Yes, the disk cache and media cache are set up in the dialog box that you showed. One caution: If they are assigned to an external volume, and the external volume is not mounted when the application is started, it may reset that path to the default location on the internal system volume. Just let students know that they should attach the external cache volume before starting up an application that uses these preferences, so that it doesn‘t reset on them.

I ask my students to always work directly on their computer to avoid problems (never work via an external drive). In other words, I ask that the active After Effects document and its linked files should all be directly stored on the computer when working on a project. I have seen too many students work via external drives and loose everything because of files being corrupted.

By @Syntax_One

I hope the video professionals here comment on this (Premiere Pro and After Effects are not my primary applications), because my understanding is that working off external volumes is extremely common in the pro video world because almost nobody has room to store all source clips and cache files on the laptop itself. Therefore students should be adept at working with external volumes.

If files are getting corrupted on external volumes, some things to think about are:

• Ensure that the cable is high quality and undamaged. It doesn’t have to be the most expensive, but at the first sign of trouble, replace it. 
• If a drive has something irreplaceable on it, it must be backed up to another drive, and that backup must be updated frequently. Students must include the cost of system-wide backup in their hardware budgets, because on a pro job, the professional cost of losing irreplaceable work because of a hardware failure will exceed the cost of the hardware. If I buy a new external drive, I always make sure I have another one with enough space to back up that external, and if not, I buy a second external drive. (I prefer to have two backup drives for every primary drive.) 

I ask because when I read: "One external SSD for original media, and Media Cache still on the internal", I wonder if you are suggesting that they put the After Effects project linked files on their external drive when working on a project.

 

Maybe I should read the following? "All media files (video, audio, vector, etc.) should be stored on the external drive to free as much space as possible on the internal SSD. However, when working on a project, all USED files should be stored directly on the internal drive."

…
Also: "Use the internal/system volume for applications only". Does that include .aep files? (Those are quite small...)

By @Syntax_One

This is all negotiable depending on how much free space there is on the internal volume.

• If everything fits internally with lots of room to spare, even when a 300-500GB Media Cache exists, then just use internal storage, no need to involve externals. 
• If space starts to become an issue, the source files and large caches are the most likely to be moved to an external volume because they collectively take up the most space. Whether you put both on the external depends on whether there is enough space to keep one on the internal. If it’s just too tight, then you offload both. Again…the exact answer depends on the sizes of source/cache files compared to the free space on the internal. 
• I don’t see any problem keeping After Effects .aep and Premiere Pro .proj files and their folders on the internal volume because like you said, they’re small. 
• Similarly, it should be fine to keep other small files like Word and Excel documents on internal storage. Basically, if all those files are not taking up a lot of space and not growing a lot, sure, keep them on the internal. 

Last think: when you say: "Use the internal/system volume for applications only (small documents are OK, like Word files) to keep free space available, and move video-related files to one or more external SSDs", how can that be done?

By @Syntax_One

For cache files, change the locations in the dialog box you showed.

For source files, just move those folders to the external volumes. The next time you open an After Effects or Premiere Pro project that used those files, they will complain that the files are missing, because the files will no longer be at their last recorded folder paths. Just use the standard relink features to point the applications to the new external location where you moved the files. Again…understanding how referenced file path links work, and how to quickly re-establish broken links because files moved, should be part of the curriculum. Link management is an essential competency because in a pro job, external drives may be passed around from computer to computer, and project/source files copied to and from them.

Adding to what others have already mentioned, I'll recommend replacing compositions that don't need further changes with exported footage. This could help with memory and processing load and can reduce the preview time in complex projects.