I’ve been thinking about the ability to move the Preview cache away from the catalog folder recently. It can be helpful for a number of reasons: Less skipping on the read head jumping between cache and library. Easier backup of images using an automatic backup, without needing to hog more space with a bloated Preview Folder. Of course being able to do this would just simply be a cool thing to do.
Warning This may eat all your files. Not really, but it is an unofficial tip and therefore you must do this AT YOUR OWN RISK. By trying this, you leave me, my provider and everyone I know free from all blame. If you lose your files and do not have an effective backup system in place the blame lies with you. Now, on with the tip.
If we try to do this by moving the file and creating an alias to the file, Lightroom ignores the alias and creates a new preview folder. Not much good to us I’m afraid. However, there is another way. The Symbolic Link. As part of it’s Unix heart, Mac OSX allows us to do a system level redirect to another location. To all intents and purposes, the file system sees this link as if it were the actual folder. You can of course create a Symbolic Link in Terminal, but if you’re afraid of command lines, never fear, help is at hand.
Symbolic Linker is a Contextual Menu Items plugin, that lets you right click on a file and create a symbolic link in the same folder.
To use this tool simply install the plugin in Library/Contextual Menu Items and then Force Quit/Relaunch Finder. Next we move the Preview Folder to its new location (if it’s an external drive, you’ll need to delete the original Preview Folder). Then we right click (or Ctrl click for one button Macs) on the folder and choose ‘Make Symbolic Link. This creates a link with the same name, but with symlink appended. Finally we move the link to the original location of the Preview Folder and rename it to remove the ‘symlink’ part. In other words, it will have the same name as the Preview Folder. If you’ve left Lightroom running when doing this, make sure you restart it, or you’ll get a whole host of errors.
Good Luck. I’ve done this with a number of catalogs and it’s working fine. I’ve not done it on my 65K images catalog yet, because the Preview folder is so big, it would take more time than I’ve had to test, but I will soon. If you try this let me know how you get on. If you decide to go back to normal, simply drag the Preview Folder back to its original location and let it overwrite the link.
For what it’s worth “ln -s /source_path /destination_path” in the Terminal command for creating a link by hand!