The licence for Lightroom allows one to run it on their primary PC and laptop as long as both are not running at the same time. Has anyone tried running it on a shared set of images (e.g., on a NAS) between a Windows PC and a Mac?

Does Lightroom create a local database/change-file or something that would prohibit this? Will I see changes made by each system and not step all over myself doing it?

EDIT: Lightroom does keep changes in a local database. However, there is an option for saving changes to XMP files (LR-defined XML files) that are kept with the images. Anyone use this method to share images and changes between two computers?

EDIT: This question was originally asked with respect to Lightroom 2.0.


Lightroom uses SQLite as the database engine. My understanding is that SQLite is unhappy if it cannot have guaranteed locking semantics for records within its file. I'm not sure what form that unhappiness can take, but accidental loss of all photo metadata is not something I'd be happy with myself.

I believe that storing the raw photos themselves on any kind of network drive is just fine. The issues have to do with the database file. Discussions I've seen at Lightroom Forums seem to back that opinion up.

If the SQLite documentation gives you some confidence, then it might be fine.

Another source of possible confusion would be sharing the same database file between Windows and Mac, but all indications are that this is not an issue. I'd test with a new (small) catalog before diving in headfirst of course.


After some extensive reading on Lightroom Forums (thanks, RBerteig!) and some other sites I've found that sharing photos and Lightroom sessions is limited at best.

You can turn on the "Automatically write changes into XMP" feature for metadata. This will allow another computer to read in the image with the appropriate changes visible -- comments, lighting changes, crops, rotations, etc. (full list of XMP tags). However, the other computer will not have access to collections, filter pre-sets, and a whole host of other meta-features that Lightroom provides since these are stored in the catalog (an SQLite DB).

Some users have pointed out that one could copy the catalog back and forth (.lvcat and .lrdata) or sync it but this could easily be done in the wrong direction and mess everything up.

From my browsing of the Lightroom Forum's it sounds like having the ability to use LR on a NAS/network is really wanted and folks are encouraged to submit a request via Adobe's Feature Request/Bug Report Form.

Some Google searches that helped:


I'm doing this right now and it works quite well if not very speedy...

Most of my pictures and my main catalogs are on external drives. If I make sure I have access to it before lauching Lightroom there's no problem.

I keep a small number of pictures and one catalog on the laptop to show/edit pictures on the go. On this computer I turned on the option to always ask which catalog to open at launch.


There is a trick you can use to store your Lightroom Catalog on a network drive in Windows XP/7. Simply map the network path as the A: or B: drive. Other drive letters will not work. Lightroom will tell you they are network drives.

After mapping the A: or B: drive, Lightroom will then allow you to save and open Lightroom catalogs from those drives, even though they are network drives. It's a hack, but it works and I know that several professional studios use this hack.

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