Auto-write changes to XMP?

[Mike Guilbault]

Does this need to be checked (or should it be checked) if you are using DNG files?

[Marc Beije]

All the LR metadata is stored in the LR database, but there are a couple of reasons you may also want to auto-write the XMP data:

• As an extra backup of (some of) the photo's metadata
• To allow other software (e.g. Bridge) to read LR's metadata

There are probably more reasons, but I think these are the main ones.

It doesn't really matter whether or not you're using DNG or your camera's raw files - in the first case, the XMP data is written into the DNG file itself, in the second case into the sidecar file. So you can use the same approach you do for raw files.

Marc

[BobSmith]

The downsides to doing this are:

1.  it slows down the program to a very noticeable degree in some circumstances as you are now causing a write operation to occur after every adjustment or metadata entry.  If you're making an entry that affects multiple files that can take a significant chunk of time to complete.

2.  you increase the chances of corruption in your files due to numerous write operations happening to your original files.  Eventually something somewhere is going to go wrong during a write operation and an image file will be corrupted.  If you notice the problem early it's generally easy to fix with a retrieval from backup.  Unfortunately the problem may go unnoticed for quite a while.  By the time you get around to needing that good backup it may be more difficult to find an uncorrupted version in older archived backups.

You have to weigh these negatives against the positive of always having your actual files up to date will all edits and metadata.  I'm not saying "don't use this feature".  Just be sure you know the potential pitfalls and consider them.  I have used that feature myself and have recommended it to others... but only rarely and in special circumstances.

Bob Smith