Make DNGs Read Only to force different workflow?

[ChrisMix86]

I recently converted all of my raw files to DNG to save some space.

I have automated backup to external drives and to OneDrive for my images and catalogs.

Because Lightroom saves develop metadata to the catalog and to the DNG file when edits are made the modification date of the DNG files are changing so often that I have the problem that as I'm using the program I am generating huge amounts of backups which is slowing the computer and network down.

The only thing that I can think of doing to stop Lr from altering the DNG files is to change them to read only. I can't see another way.

I know that in preferences one can stop metadata being written to .tif , .psd etc and to proprietary raw files; sidecar files are created instead

Has anyone had the same problem and found a better solution?

[dj_paige]

By default, LR does not write to your DNG files.

The preference you mention also applies to automatically writing the metadata and edits to DNG files. Make sure it is turned off.

[Ian Lyons]

dj_paige  wrote

The preference you mention also applies to automatically writing the metadata and edits to DNG files. Make sure it is turned off.

I believe you may be confusing 'PNG' with 'DNG'. Activating the preference mentioned above does not affect DNG.

[GoldingD]

Actually the OP does mean DNG, and the OP is correct about metadata written into DNG, and yes a method exists to prevent the issue

read

DNG Pros, Cons and Myths | Adobe Blog

pay at attention to “Backing up DNG metadata changes”

[ChrisMix86]

Thanks for all replies.

David, the blog section you mention does say that one of the cons of converting to DNG is that you get the problem I talked about, but it doesn't offer a fix (the assumption is don't convert your raw files to DNG) and that's why it's listed as a con Also Ian wasn't talking about me mixing up PNG and DNG, he was talking about dj_paige who he quotes.

I have a workaround but it's not that great. The first checkbox just stops Lr from writing metadata to JPEG, TIFF, PNG and PSD files.  The second stops Lr from writing XMP, which after testing looks like it doesn't just mean the sidecar files but actually writing metadata into the DNG files.

I wish there was an option to keep writing xmp sidecar files so that Lr would handle DNG files just like proprietary raw files. I'll just have to backup the catalog more often.

[john beardsworth]

In Bridge, making a DNG read-only forces Bridge to create xmp sidecars. Lightroom doesn't work that way, and I don't believe there is a way to force it to do so.

In any case, remember that the xmp does not contain all your Lightroom work. Depending on how you use LR, that could be a lot - VCs, stacks, flags, collections, history steps.... The xmp is designed for data exchange with other applications - not primarily for backup. To backup your work, yes, you must backup the catalogue more often.

So you are going to have to find a way to fine tune your backup software so that it backs up new DNGs, but not changed ones, and to backup your catalogue, which contains your work. One way might be to point the backup software at one folder/drive where new DNGs appear, and then move the DNGs to another folder/drive which isn't backed up by the same software.

[TheDigitalDog]

This is really one of the few disadvantages of DNG. But the same would be true for a TIFF, PSD or JPEG; any change within the document will 'force' an update for backup. But really, it's best to do so and if the backup takes place unattended as many do, not a major issue.

[Rob_Cullen]

In Catalog Preferences/Metadata tab-

This option will write metadata into DNG files whenever you edit an image in any way. It changes the DNG file such that backup software will identify every write of metadata as a 'new' file that must be backed up entirely again. An XMP sidecar file is not created.

This option does NOT write metadata into DNG files. The DNGs are not modified. They never need repeated backups. All editing and metadata changes are stored in the Lr Catalog, and the Catalog must be regularly backed up!!

I convert all my Nikon files to DNG, I use Syncback to backup my DNG images. Syncback only ever identifies new DNGs to be added to backups.

[GoldingD]

So, an experiment

Part 1, results in Windows File Explorer (properties)

Situation 1, in Catalog Settings XMP on

Exported a RAW file to a DNG file in LR

In Windows File Explorer  looked at the DNG files properties, added date created and date modified to fields looking at, noted the time(s)

In Develop module, underexpose on purpose, fiddle with a few other sliders just to take up

Close LR, go back to Windows File Explore.

Yep Date Modified changes.

Situation 2, XMP Off

Back in LR, turn XMP off, in develop module reset the image, went for way way over exposure, fiddled, spent time in develop module.

Exit LR, back to Windows File Explorer,

Nope date modified no change (time)

Part 2, Can changes bee seen outside of LR

Situation 1, XMP on

Back in LR, turn XMP on, tweak the image, exit LR, bring up windows File Explorer, right click, selecy Open With.

Open with Photos: no visible mods to image

Open with PS:Yes in ACR, mods visable

Situation 2, XMP off

Open with Photos: no visible mods to image

Open with PS: no visable mods to image (ACR)

Now, remember, with XMP on, if it was a RAW file, I would see an XMP accommodating the RAW file, but for the DNG, no such thing. The data that would go into the XMP file got written into the DNG file.

[ChrisMix86]

Exactly and what's annoying is you can prevent Lr from changing other files, even .psd, but it insists on writing  xmp data directly to the DNG file or not at all.

This is really one of the few disadvantages of DNG. But the same would be true for a TIFF, PSD or JPEG

It's quite the same for those, I think they can be left in peace and Lr will create sidecar files for them.  As John says, Bridge will do this for DNG.

Really appreciate all the replies and input, every single post has been helpful in some way or another.