This conversation has been merged. Please reference the main conversation: Lightroom/Camera Raw: Store the xmp metadata outside DNG, jpeg etc file to be backup efficient
I have used XMP files since the very beginning of Lightroom. It's a handy way of having an "instant backup" of changes just in case something ever happens to my Lightroom Catalog. I love the safety net that XMP files give me.
A year and a half ago (after 15 years with Canon) I switched to the Sony a7iii. The biggest downside to that is that Sony's ARW files are 47mb each. But if I use the Adobe DNG Converter, I can losslessly compress them down to just 27mb each. As I shoot thousands upon thousands of images each month, that 20mb per image savings is huge. Especially when you take into account backups.
However, there is one big thing I hate about using DNG files. And that is that every time I make a change in Lightroom (change a star rating, adjust exposure, crop, etc) that 27mb DNG file needs to be backed up. AGAIN. Because unlike my Canon raw files, with XMP sidecar files, the DNG files are written back to whenever I make any changes.
Is there any way to change Lightroom to write to a tiny XMP file every time I make a change, rather than modifying my 27mb DNG files? I would much rather backup and rebackup tiny little XMP files. It makes no sense to have to backup an entire 27mb file just because a few bytes inside of it have changed. And it costs me money (I have to pay extra to Internet provider as I go over their imposed limits).
For a real world example, let's say I shoot 64GB worth of files for a wedding. It backs up 64GB worth of files right after I get home and import the files into my system. It'll be a few weeks before I get to the wedding, but when I do, I'm going to rate all of the images. Now they all get backed up again (that's an extra 64GB needlessly being backed up). I probably won't finish all of my edits in one day, so the next day as I continue editing... any remaining files that get changed will be backed up again. And again. And again, for as long as I keep making changes inside of Lightroom. See how this is suboptimal? Certainly it's not a lot of money, but it all adds up and is costing me extra for my Internet usage because it is metered. Whereas if it was using XMP files, then only tiny (what, 10K?) files change as I make my LR edits and that is all that has to be backed up, with XMP files the much larger raw files remain unchanged.
So for me ... DNG storing internally any changes is expensive. I would love to have an XMP option if it were available. It would reduce how often my local drives get hit with backups as well as the my internet cost for backing them up.