How do you manage data on very large discs?

I have two disks in each computer - one for the OS & applications, one for my data. The data disks vary - up to 2TB.

About "I should back up these partitions perhaps every 3 months or so" - I imagine this was a typo. If it wasn't then it hardly seems worthwhile helping you because it is all going to end in disaster anyway.

I'd suggest thinking through your backup policy. Anything that is best backed up & restored in the same way [imaging, simple file copying, ...] can be in the same partition.
1 I have an OS partition on each computer - my diary contains the note to image this weekly but I often skip weeks if there have been no substantial changes. I retain the last few images and weed out older ones except significant ones. All images are made onto [alternately] one of a pair of external drives. The images are saved in separate folders not in separate partitions.
2 I have a Maps partition on each computer [for maps of the MS Maps App] - this gets imaged once in every blue moon because that's how often I change anything.
3 I have a data partition on each computer for my own 'conventional' files. These are backed up using the built-in utility RoboCopy - hourly to a set of mirror folders in an SD card that lives in the computer, "weekly" to an external drive.
4 I have another data partition on each computer for my large collection of audio files and for my recent TV recordings. These are backed up using the built-in utility RoboCopy - new/changed files only are backed up hourly to a set of mirror folders in the same SD card that lives in the computer, all files are backed up "weekly" to an external drive.
- [The files are removed from the SD card when they have been backed up to the external drive. The SD card is not used for an accumulation of backups but merely for a single, automatically-maintained set of file copies.]

I think your extraordinary number of partitions is unnecessary and achieves nothing for you. I appreciate that you regard them as helping you avoid mistakes.
I also think separating system images into separate partitions is a complete & utter waste of time.

Best of luck,
Denis

Ford Prefect said:

Thanks very much for your interest and for your "suggestions", I've tried fewer partitions and using folders but it doesn't give the separation and it didn't work for me, it's too easy to end up with hundreds of folders which become a nightmare to monitor.
Do you actually manage very large discs and data?
If so, I'm interested in what you actually do, rather than suggestions.
I'd like to here from people who have been there and done it!
Thanks again.

I also have this issue, perhaps not as many files or TB, but the issue is the same. I also have just one MEDIA drive, with top-level folders like:
iTunes (since I have iPhone and iPad devices)
Photo
Photo-Exported
PhotoToImport
Books (PDFs, mainly)

By the way, I do all my photo work in Lightroom and I use the YYYY\MM\DD structure inside all the photo folders. To manage things properly, I rely on Lightroom's keywords and collections features. Some people have over 500,000 images in their Lightroom catalog, which just is an information repository for all your files on disk. Works great, but the downside is that if you want to move photos to a different folder location, you have to do it within Lightroom.

OP, concerning backups: you can make one full image of each partition, one partition = one full image. Your OS partition and any related hidden partitions can be one full image. Then, each of your data partitions gets one full image. No more mixing OS and data. And, naturally, as the data in each partition changes, simply update that particular's partition's full image - maybe once weekly, or bi-monthly at least. This might have already been suggested earlier by others.

Actually, your data partitions remind me of a church elder, using a 286 or 386, on a 100MB HDD, had to form many partitions because DOS at that time could only handle 1-20MB per partition.