P: Allow Catalog to be stored on a networked drive.

As TK says above, "Use at your own Peril". Adobe specifcally says that use of the catalog on a Network drive is not supported, so personally I wouldn't even fiddle with any of the workarounds, even for single-user use.

Here's just one of many references on adobe.com: http://kb2.adobe.com/cps/406/kb406369...

If I remember correctly, Dan Tull was experimenting with simultaneous accesses to see whether the sqlite locking problems would indeed be prohibitive, as referred to above by John Ellis, and since there were problems, it confirmed the hunch that a full-blown network solution was not feasible for now. He was *not* testing the one-at-a-time "trick" as is being suggested here for the interim, which from what I've been able to gather, may not be problematic.

Dan Tull did do some tests and managed to repeatedly corrupt his catalogs beyond repair, just as a result of the network connection dropping at the wrong moment. That's not to say that they won't find a way round it, but there are legitimate reasons why it hasn't happened yet.

Thanks, John, that's very useful information. It appears that one could stay out of trouble by making sure that there are no access conflicts. I understand that even commercial studios use the network "trick" without problems.

Lightroom uses the SQLite database engine. A couple of years ago, I investigated the issue of running SQLite with database files residing on network volumes, and I found numerous people advising not to do it. The advice all seems to originate from this paragraph at the SQLite site:

http://www.sqlite.org/lockingv3.html
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"SQLite uses POSIX advisory locks to implement locking on Unix. On Windows it uses the LockFile(), LockFileEx(), and UnlockFile() system calls. SQLite assumes that these system calls all work as advertised. If that is not the case, then database corruption can result. One should note that POSIX advisory locking is known to be buggy or even unimplemented on many NFS implementations (including recent versions of Mac OS X) and that there are reports of locking problems for network filesystems under Windows. Your best defense is to not use SQLite for files on a network filesystem."
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But I didn't find any seemingly reliable reports of anyone who actually experienced corruption that could be definitively attributed to a Windows file server. That doesn't mean there aren't any, of course.

I know several people who've tried this and said it worked, but none I know have reported performance benchmarks nor if any problems had been encountered after using it this way for a long time. I'm still wondering how much peril there might be, and what kind of performance hit there might be - networks can be pretty zippy these days... If anybody tries this, *please* report your experience to the rest of us...

FWIW, there is a current workaround that fools LR to believe that a catalogue on a shared network drive appears to be on a local drive.

One can, for instance, make a drive letter substitution using the Windows command shell, e.g., "subst A: N:\Lightroom" which would make any catalogues on the network drive "N:" in folder "Lightroom" available through drive "A:".

An alternative uses a symbolic link.

Of course, performance will suffer and only one user can use one catalogue at a time. Accidental concurrent access might even be automatically excluded by LR's use of a "lock" file.

Use at your own peril.

I used to do so until it corrupted my database for some unknown reason.
I still have the catalog if you wish.
concerning the network option, you could simply use a lock mecanism. It is very effective.
Just log an entry in the DB or a file for the first user that opens it. As long as his session remains open that entry locks the catalog, any other user can view it but not modify anything in it.
during a session or if there is a crash, the user should be able to release the lock. In this case he looses the possibility to edit the database until he re-launch lightroom. In the meantime anyone that would open the catalog would of course lock it, unless you add an otpion to open in read only mode.
regards

PS : I just read a bug on jpeg and metadata. If you think this is not related do not hesitate to ask me more detail, I will be happy to help. Menwhile I will check all of my jpegs.

Thanks John, i will have to try that out again, but that only solves part of my problem (getting pictures on and off the laptop).
Having the database on a server to be used in more than one PC at the same time vould be helpfull and allow for better backup and security for the pictures. If the database was on a server it could be on a expandable disksystem (eg. iSCSI or SAN) that would allow the database to grow as pictures are added.

We are a media department at a community college that uses Adobe products. We would love to be able to use Lightroom as a department with centralized catalog(s) on a network drive. Benefits are concurrent use, ability for all staff to search the catalog, inclusion in IT-driven backup, redundancy and recovery and ease of use. Non-IT Individuals responsible for database maintenance is not the best way to safeguard our college's photo collection.