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Photoshop Lightroom Reference Guide

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Don't Let Lightroom Take Over Your Hard Drive

Last updated Apr 25, 2008.

Lightroom doesn’t want to take over your hard drive, but it needs your help to prevent this from happening. The reason so many people encounter this issue at some point is that the default location for the Lightroom catalog is in a folder (also named Lightroom) on your start up drive.

On Windows: My Pictures/Lightroom

On Mac: Pictures/Lightroom

Inside this folder you will find the Lightroom catalog, which has an .lrcat file extension, and the Lightroom preview cache, which has an .lrdata file extension. If you want to get a better handle on the relationship between your Lightroom catalog and your actual photos I strongly recommend that you watch this video tutorial by George Jardine. The most important thing you need to know is that the catalog file (.lrcat) is where all your Lightroom work is stored. This is one of the most valuable files on your disk, so take the time to back it up.

There is nothing wrong with keeping the Lightroom folder on your startup drive if you have ample space, but you want to keep your startup drive at least 20% free (50% free is better) because other programs use that free space for normal operation. If you have too little free space you may start having problems across the board.

So, let’s look at what you can do to manage this situation to your advantage.

Another default setting that can impact your free space is the aforementioned catalog backup. If you don’t manually choose where to have your backup catalogs saved Lightroom saves them to the Lightroom folder on the startup drive! This is not ideal for 2 reasons. First, you don’t want your backup copy to be on the same drive as your original catalog because if your drive fails you lose the back up too. Second, each time a backup process runs it creates a new copy of your catalog, which over time can eat up quite a bit of disk space. So check out my previous tutorial on catalog backups to learn how to direct those copies to a different disk.

Next, let’s take a look at some of Lightroom’s settings that can impact the size of the Lightroom folder. Go to Edit > Catalog Settings > General (Lightroom > Catalog Settings > General on Mac).

The General tab is sort of like the dashboard on your car; it can tell you a lot about the Lightroom catalog. If you ever forget where the catalog is located you can open this dialog and find it simply by clicking the Show button.

Click on the File Handling tab. There are 3 settings here that have an impact on the size of the preview cache. Ideally you only need your Standard Preview Size set to be about the same size as your monitor’s resolution. So, on my MacBook Pro, which runs at 1440x900, I have my previews set to 1440. While on my Windows desktop running a larger and higher resolution display, set to 1920x1200, I set the preview size to 1680. This controls the maximum pixel width of the standard size preview files, and the smaller the file the less space they require.

The next setting to configure is the Preview Quality. The default setting of Medium is just fine. Think of this as the amount of JPG compression applied to the preview files. The more compression the smaller the file size. Medium is a good compromise between file size and quality.

The last setting to consider is the schedule for discarding 1:1 previews. A 1:1 preview is what you look at when viewing your photos at 1:1 (i.e., full size or 100%) in the Library module. This is essentially a full size JPG copy of your photo. So, after awhile these can really take up a lot of space! The purpose of any cache is to speed up viewing time by keeping a copy at the ready whenever you need it. However, Lightroom will always render new 1:1 previews as needed, so if space is tight change that setting to discard After One Week to help keep a lid on the growth of the preview cache.

The last step is to switch back to the General tab and look to the bottom for a button labeled Relaunch and Optimize. Clicking this button is a painless way to possibly reduce the size of the .lrcat file. Just click it and Lightroom will do the rest.

One last thing to consider is to move your entire Lightroom folder (the one that contains the catalog and previews) off the startup drive. Another internal drive would be ideal, but an external drive with a fast connection will work just fine. Here’s how:

Step 1.

Close Lightroom.

Step 2.

Open Windows Explorer (Finder on Mac), navigate to My Pictures (Pictures on Mac) and select the Lightroom folder.

Step 3.

Move the entire folder to the drive of your choice. If you have the resources you might consider dedicating a single (large capacity) external drive just to holding the Lightroom folder. That way it can grow as needed without impacting anything else.

Step 4.

After the move operation is complete, open the Lightroom folder at the new location and double-click the .lrcat file to open it in Lightroom. Lightroom will then store this new location in its preference file so it will open it automatically in the future. You can also go to Edit > Preferences > General (Lightroom > Preferences > General on Mac) and hardwire the default catalog (this is what I do) by configuring it at this location.

Hopefully this will put your startup drive back in the safe zone and make your Lightroom experience much more trouble-free.