Adobe Software and Memory Problems

Yes, there is "smart management" and PS will use the drives listed in the listed order (and you can change the order):

When Photoshop closes, all scratch files are deleted. While open, the allocated disk space will be reused as needed.

Again, your issues have nothing to do with PS per se. Your disks somehow "forget" that PS is accessing them and that can mean anything from botched storage drivers to misconfigured power management sending them to sleep at the wrong time. You really have to give us all the info before anyone can even guess. Under normal conditions PS always cleans up after itself, so what you see is definitely not normal or intended.

Mylenium

Thanks for your replies, but I don't agree with my computer being flawed somewhere as no other software encounters any problem of this kind. I moved the TEMP/TMP folders as suggested (thanks a lot for this tip !), and I hope it may help, but the problem is that PS doesn't seem to take into account the scratch disks and use, for all its history and rasterizing needs, the Windows drive. 

I don't know what you need exactly but I have no hardware limitation as such, but for C:\. Indeed, my RAM is 16GB, I have 3 disks with a total of about 8TB of free space and a graphic card that is fair too, so the problem does occur from the mismanagement of the temporary files, according to me.

That may be a naive question, but isn't there a smart management of the temp files from PS or Premiere Pro, like when you reach mybe 90% of the disk memory, it switches to another one? I'd like to run a test to see whether they are effectively using the other scratch disks. Does such a thing exist?

Thanks again for your support!

Without exact system info we can't tell you much. the simple truth is that your disks don't work correctly and this is not a general PS or Premiere problem. 50 GB is plenty to work with and if you're working with regular file there's no need to habve more, contrary to what Mr. Fosse said. So no, that's not an issue you can fix from within the Adobe apps. Start by monitoring your task manager and resource monitor and verify your disk setup via the disk management system control. Also check your device manager and install/ update all necessary drivers for your storage devices.

Mylenium

Have I missed something?

Yes. This isn't Photoshop - it's a lot of data and you need to have space for it.

Raster image editing moves massive amounts of data around, much more than any RAM you may have installed. All that temporary working data has to go somewhere, and so it's written to disk. This is Photoshop's scratch disk.

The scratch disk is Photoshop's main memory, with RAM acting as a cache. Data go back and forth. The scratch file contains all history states for all open documents, plus overhead (which in the case of smart objects can be very large) The scratch file will be orders of magnitude bigger than the nominal starting file sizes.

Bottom line is, you need at least 500GB free space for the scratch disk, maybe more. It depends on what you do.

Moving Photoshop to a different drive accomplishes nothing except other potential problems. I'd recommend putting it back on C.

Your free space is pretty marginal, especially if exporting videos. Also, if you use Premiere Pro, there are cache locations, but that's rather off topic here. If your other drives are internal, you could consider moving %TEMP% to one of the other internal drives, which is discussed here - https://answers.microsoft.com/en-us/windows/forum/all/change-location-of-temp-files-folder-to-another/19f13330-dde1-404c-aa27-a76c0b450818

Hi!

Thanks for your quick answer.

I have precisely more 50 GB of free space on the Windows disk and more than 8 TB on the others. About the hidden files... well, technically, they are hidden, so it's hard to spot! But it seems that they were in the %temp% folder, linked with the  opened Windows account. And I know that because when I check the disk memory, after a few project files, it drops to zero, or so. And even without it, I receive error messages (like when I want to export a movie, or a PSD into a picture format).

How much free space are we talking about, here? You should never get below 50-100GB on your system drive, it's asking for crashing, performance reduced (permanently), and more.

You say "hidden" files are still around? How do you know, and where are they?