Thomas Dalton wrote:
How do image description pages work with this setup? If you upload an image on one wiki, the database for the other wiki won't know anything about it, so what does it show for the file history, etc?
Yes, that's right. Since the default upload mechanism isn't altered, the behaviour is as expected: If I upload to site1, the image description appears at site1 (and not at site2), and vice versa.
To make the images available to both sites, I'm running ./maintenance/rebuildImages.php on a regular basis with a Cron job; that takes only a few seconds and causes neglectable server load (surely this wouldn't work anymore if we had several 100k images). And, of course this doesn't replicate the descriptions itself; we can do this since it's our own data that we share between the two wikis and we know the file's names, but obviously such an setup wouldn't be advisable on a site like Commons where correct licensing is crucial.
I think, however, if you used a Wikipedia dump and added the matching image files with a script, description pages would go bonkers in any case (our simple setup, or the "pool" setup). I haven't tried this yet, but I think the image descriptions from the XML dumps become useless as soon as you utilize some kind of shared data storage (correct me if I'm wrong). As always, it all depends on what you try to accomplish ;)
Greetings, -asb