Hi Sven,

Do you happen to have a modern, large thumb drive (modern = fast usb3) ?
If yes, look into rpi-clone utility.
github.com/billw2/rpi-clone

It only clones used space, skipping temp files/directories created by the kernel/utilites and not needed across boots

If your PI4 is up to date firmware wise, rpiclone can give you a bootable thumbdrive which could be cloned back to the SD card if needed, or mounted after boot if need something off of it.

How much space is being used currently, a 'df -k' command in a shell will show percentages.

Gene

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