[Boyzie]

When backing up tMM should one do a back up from
\Tiny MediaManager\cache
and / or
\Tiny MediaManager\cache\image
as well?

Or can tMM automatically do a back up?

[myron]

depends.
These are the shrinked and cached images from your datasource. (posters, fanarts, ...)
If you want to browse TMM with images, while your HDD is disconnected, it makes sense to keep them.
But it will always rebuild when needed (if activated), so.... it's up to you to decide

Usually, you only need to backup /data/

[Boyzie]

If you want to browse TMM with images, while your HDD is disconnected,

Yes, that is what I want so I better will go on backing them up as well.

But it will always rebuild when needed (if activated), so

So if the drive with TMM crashed / the data were lost TMM simply - after re-installing it on a new drive and copy back its data folder - could rebuild the images with the so named option in the menu after plugging in the external drives.