Tuesday, 18 March 2008

Running Lightroom on two computers with the same catalog

When I decided to commit to Lightroom I also effectively committed myself to keywording my initial library of 6,000 photos and to keyword new images as I created them. This was not going to happen overnight and I quickly realised that I was going to want to work on them on more than one computer - Would this mean that I needed to buy a second copy of Lightroom and was it technically possible?

First why exactly do I need to work on more than one computer? Well, my primary computer for working on images is a reasonably specified desktop PC with a largish LCD calibrated monitor, Wacom graphics tablet and sundry attached devices. But this is in my office and I often found myself wanting to be less anti-social and able to work on a laptop just entering the keywords and doing general image management.

First off I was not willing to buy a second copy of Lightroom for this, but I did discover in one of my initial Lightroom learning sources that it was legal to have two copies installed with one purchase. To confirm this I looked up Adobe’s web site and found the following definitive statement in their Lightroom FAQs:

“How many computers are covered by a single license of Photoshop Lightroom 1.1?
Subject to the terms of the End User Licensing Agreement, the primary user of the computer on which Photohop Lightroom (the “Software”) is installed may install a second copy of the Software for his or her exclusive use on either a portable computer or a computer located at his or her home, provided that the Software on the portable or home computer is not used at the same time as the Software on the primary computer. You may be required to contact Adobe in order to make a second copy. Photoshop Lightroom is sold as multi-platform software, which means it can be installed on either Mac OS X or Windows.”
Unless Adobe read this posting and correct their spelling of Photohop (sic) in this FAQ that is how they spell it…

More seriously this clearly says that running two copies on different computers is legal and since I can find no reference to this being changed for v1.3 I assume it still is, and I sincerely hope it remains so.

So is it technically possible? Simply – Yes, and it is easy to do. Since Lightroom does not need access to the original full size image files to work on things like keywording; it only needs access to the previews Lightroom automatically generates when it imports the images in the first place you only need to have the catalog and previews available to work on them. Only if you want to process the images (e.g. create TIFF files from RAW etc) does Lightroom need access to the original file.

Here’s how I did it:
  1. I bought a USB powered 120Gb LaCie Rugged external hard drive (see photo below) – I wanted it to be USB powered as it would be much easier to move it around without the power brick to power it. I forced the drive letter to “Y” so that I will not get confused with any other drive I might have installed temporarily.

  2. I had originally installed Lightroom with its default settings and have so far only worked with one catalog. I had also set it to prompt for backup every time it starts up. This makes a backup copy of the current catalog and stores it wherever you want it stored (in my case the default “My Pictures” folder). I found the copy of the catalog on my desktop’s internal hard drive in the default location: “Program Files=>Adobe=>Adobe Photoshop Lightroom 1.3”. I copied this up to my normal backup external hard drive in case of accidents. With the frequent backups that I had made already this was not really necessary, but I really, really did not want to lose the work I had done so far, so a belt & braces approach seemed the best bet.

  3. I then instructed Lightroom to export a copy of the catalog to the LaCie (Y:) drive. Since to use the catalog you also need the previews I ticked the box to include them with the export (circled in the screenshot below).

    If you want to see a full size view of any of the
    screenshots just click on the image

  4. I then (with everything crossed) deleted the original Catalog and previews from the internal drive.

  5. I then started up Lightroom, skipping the backup option on start-up. The screen below popped up (this is actually the screen I get when I unplug the LaCie drive with the catalog on it, but the principle is the same). I chose the “Select Catalog” option (circled) and navigated it to the new copy of the catalog on the LaCie drive. Lightroom then started up as if nothing had happened.

    Currently there are 6,703 files in the Lightroom folder on the LaCie drive for 6,695 images – 6,701 of them are catalog previews, taking up 7.3Gb of space. The single “Lightroom Catalog” file is 90.1Mb.

  6. I then installed a second copy of Lightroom on to a laptop. When it started up there were (not surprisingly) no photographs. I plugged in the LaCie drive and told Lightroom to "Open Catalog" (Ctrl+O); I navigated to the catalog on the LaCie drive. Lightroom then re-launched itself using the new Catalog, et voilĂ , it worked…

    As you can see in the screenshot below the previews, keywords (circled in screenshot) and other metadata are all there. The only real difference is that there is a "?" in the top right hand corner of each thumbnail (circled in screenshot) which is Lightroom telling you that it can not find the original image file; again not surprising as they are not on the laptop anywhere.

It really was very easy, although worrying. Using the two machines has been easy and so far I have not experienced any problems. I still have quite a lot of keywording to do though…

I have continued to backup the catalog on the internal hard discs of each machine every time I start Lightroom, so that I now have multiple backups of the catalog. Every now and then I delete old catalog backups as I can not see any reason to keep them beyond a few versions and each backup is the same size as the current catalog (around 90Mb each time at the moment).

I have not noticed any performance degradation with the catalog and previews on the external drive instead of the internal one – I am very happy with the set up.


Thomas said...

I prefer Imatch from www.photools.com for keywording, the editor is simply better - and the database is open for import and export also with different formats.

Unknown said...

Very informative and well written post! Quite interesting and nice topic chosen for the post.

Acer - 13.3" Aspire Laptop - 4GB Memory - 500GB Hard Drive - Cobalt Blue

Acer - 15.6" Aspire Laptop - 6GB Memory - 500GB Hard Drive - Smokey Black

Unknown said...


I figured out how to have a single catalog on multiple machines with the photos shared on a NAS on my network. Its similar to using dropbox or Google drive but there is no size limitation on catalogs


Ive been using it for a couple of months without problems and it syncs up really quickly. It can even keep the different machines in sync if they are in different locations just over the internet.