Share LR CC Catalog Catalog between Desktop and Laptop?

[LoveWaterfalls]

Hi Folks,

I have all of my pictures stored on my Synology NAS. I access them now from my Desktop computer (Windows 10) using LR CC (I started with LR3) with my catalog stored on my local HDD (Drive D:\My Pictures\Lightroom). I have also installed LR CC on my new laptop (Windows 10). I want to use the same catalog in both computers. Using Google I just cannot find any reliable answers to the question on how exactly to do this. I do hope someday Adobe provides official setup instructions on how to do so and makes LR a network capable program. Both computers have access to the NAS and the Pictures folder on it. How do I setup the catalog on the Desktop PC so that I can copy the catalog files over to my laptop and see the exact same pictures and all of my LR edits? Any and all working solutions from those with a similar setup would be appreciated. Thanks so much. 🙂

Roger

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[F. McLion · Accepted solution]

With on-board tools, this is not possible - many have this on top of the wish-list.

Here is some reading for you:

A Portable Lightroom Catalog - Mike Hoffman

https://www.lightroomqueen.com/how-to-lightroom-catalog-multiple-computers/

How to Use Lightroom on 2 Computers and Keep the Catalogue Synchronised

[zulucowboy]

You would think with many having it on their wish list adobe would listen.

[F. McLion]

It is not on the road-map for LR Classic CC and I do not expect that this will change - unfortunately.

[Ed33694885zcmb]

Hi All, so the question is: how can I work on the same LR catalog on multiple machines. Note: NEVER at the same time, but that's kinda logical because if I am editing on my macbook then I am probably not wanting to edit the same catalog on my macstudio. But what I frequently do is do an initial culling on my macbook lying on the couch, and the next day I'll pick up where I was on my macstudio and start editing the 10 hero shots. I really think this is a very realistic scenario for many folks, and I don't understand why adobe doesn't care to support this. FYI, Capture One does support this use case. Just saying.

The ironic thing is that adobe LRC has it 99% implemented already. When you start up LRC it creates a file named <mycatalog>.lrcat.lock. This is a very simple file that only contains the app name (fullly qualified file name for LRC) plus the PID. This is the App ID that the running instance was given by the operating system when the app was launched. When you (accidentally) try to start up a second instance on the same computer the first thing that second instance does is check if there is a lock file already for the catalog that it tries to open, and if there is, then the second instance will shut down immediately. So, LRC is therefore a deliberate singleton process on a computer. When the first instance is closed, the last thing LRC does before shutting down completely is deleting that lock file, so that it can start up next time. The reason that PID is in there is probably because if LRC crashes, then it doesn't have an opportunity to delete the lock file, and then when it starts up later it'll think that LRC is already running, and erroneously shut down itself. So in this case LRC does an extra check and check with the Operating System if there is indeed an instance of LRC running with the PID listed in the lock file. If there is then the app really needs to shut down immediately, but if there isn't a LRC instance running with that PID then you may get an "LRC noticed that it crashed before and we may do x, y or z".

Anyway, as I mentioned, Capture One does support this on multiple computers and I think that the difference is that C1 doesn't check the PID, and hence it is usable as a lock mechanism not just for creating a singleton mechanism on the same computer but also as a singleton mechanism between multiple computers. Using a Synology NAS, or similar, is a great way of doing that. A NAS usually has a mechanism to synchronise files between multiple computers. So what I do is have my catalog synchronised with a directory on my NAS, and from there it is synchronised with my second computer. From LRC perspective, the catalog is running local on the disk, which solves performance issues that LRC would have when storing a catalog on a network drive, but the sync ensures that both machines have the same content. Of course, syncing takes time, so if I upload 3000 raw files to one machine, it'll take an hour or so before the other machine has them too. In practice, this never is an issue, just something you need to be aware of. Now here comes the tricky part. At the moment, the lock file mechanism DOES NOT work in the NAS sync scenario. Worse even, since it is synced between both computers, whichever LRC instance is closed first will delete the lock file, which will then be synced to the other computer and hence deleted there as well even if there's still an LRC instance running on that second computer.

So two things need to happen:

1) The lock file needs to be excluded from the sync so that it stays local to each machine and can do it's designed task, which is to prevent multiple LRC instances running on the same machine, and

2) some scripting magic is needed to check if an instance is running on 'the other' machine and pending the outcome decide if it's OK to start up or silently fail.

This is doable, and it's possible to make it relatively safe, but it would be far far better if Adobe just enhanced it's lock functionality to support collaboration between two computers working on the same file. Again, Capture One supports this. They also create a lock file (named writelock) and they store the user name and a GUID in there. Not sure how they use that to still enforce a singleton on the local machine, but it works 100% reliable in the described synology sync solution. 

Hope this clarified things a bit.

[JohanElzenga]

Sharing a catalog between two machines is already possible, and only requires a bit of carefulness. What you can do is store the catalog in a local folder that is synced to the cloud, such as what Dropbox offers. What is important is that the catalog remains local, so do not use the 'online only' setting that Dropbox offers. The carefulness that is required is that you must make sure that Lightroom Classic is not still running, Dropbox had enough time to sync from the machine you last used to the cloud before you turn off that machine, and enough time to sync from the cloud to the other computer, before you start Lightroom on that other computer.

If you use two local computers located in the same house, then you can simply use a synchronization utility to sync the catalog folders over your local network and don't need the cloud at all. Just use the same common sense, only sync when Lightroom Classic is not running, then you won't need anything special like a check for .lock files.