RPi4 & HDD corruption

    About "write-caching" and 6TB NTFS... no idea. I used once for few hours a HDD as "File server". As I don't need big a storage, and for me was too anoying the noise of the drive... replaced with a cheap 32GB USB stick (now 128GB). Also anything what mechanically moving... wears out... (I'm an eficiency maniac ;) ).

    Another side, even if the data coruption will be almost eliminated, I don't think to be safe for data and hardware the "just flip the power switch" method. If the power go down when the HDD working (write cycle), is some chance to damage the HDD (head or disk fault). And losing some TB of data... Few years ago, I strugled a day to recover only 5GB of data (vacation pictures and movies) for a good friend from an defective HDD...

    If you have power cuts (or use the power switch), maybe could be an idea to use an SSD (no moving parts :) ) for "active data" (TV recording, etc.) and once a day or week to move it to HDD. The HDD most of time can be in IDLE (hdparm), and the data copy/move can be resolved automatically with a cron job.

    I agree with pretty much all you posted. Most of the time with the Pi3 I've transferred videos and just left things running. Generally I don't just turn things off, I've done it with the Pi4 partly to try and find out what's happening and what's safe.

    I do have a 120GB SSD which is used for boot and recording. I found with the Pi3 that it was best to write to the boot device. Most of the stuff recorded from TV never makes it to the HDD, mainly because its rubbish - difficult to pick only the good films from the descriptions :(

    I'd love an SSD for main storage as well, its only the price that stops me.

    Just tested with the 6TB disk and write caching is still not supported with exFAT but the good news is that the disk isn't corrupted. I can only think its to do with the journaling in NTFS / Ext4.

    BUT, since I now have something that works, I don't care - Yippee