Working with Lightroom Classic and Photoshop from an external (online) drive

As already mentioned you can set a different installation location, and you can set a different location for the original photos and videos. But there is a little more to think about.

With Lightrooom Classic, the folder containing the preview cache files (.lrdata) can, over time, grow to be larger than its catalog, but many people aren’t paying attention to the space consumption of previews. The previews are stored in the folder in which you store a catalog, so this can be solved by keeping the catalog on an external volume, like maybne where the photos are.

With Photoshop, there’s a similar cache file that can consume similar large amounts of storage, called the scratch file. Unlike Lightroom Classic previews, the scratch file is deleted when you exit Photoshop. But during a Photoshop session, if the cache file use all remaining storage because of low free space, that can lead to slowdowns and crashes. The solution is in Photoshop Preferences > Scratch Disks: Assign the primary scratch disk to a fast external volume with at least a couple hundred GB of free space.

I am also a laptop user, so what the above means is that I often run with multiple external volumes mounted. One is a large SSD with all my photos and videos on it, and another is a large empty SSD used only for performance caches (Photoshop scratch file, video editor cache files, etc. all of which can become very large).

To simplify this setup at my desk, the SSDs are normally connected to a fast hub that can also provide power to my laptop. So I plug the laptop into a hub with one cable, and that connects power and the two SSDs (and other hardware such as displays).

All my photos are currently stored on my computer. Could I store them in an online storage space and still be able to use them in Lightroom and Photoshop?…Hopefully someone knows if I can use the programs from an online storage location! Otherwise, I think I’ll have to consider making a big investment…

By @Bo Tuijp

There are two different questions there. The first is if you can use your photos from an online location, and if you can use the programs from an online location. 

Using the photos online. If you mean using a synced online storage location such as OneDrive, Google Drive, or Dropbox, this is possible, but probably won’t solve your problem. It’s possible when the originals are still on your own computer. You edit them from your computer and the changes sync up, but the problem is you’re not saving any space on your computer. So, you can turn on the feature that evicts the files from local storage and only keeps them in the cloud. But this is risky because it might not work reliably. For example, if you want an app (such as Photoshop) to open a file that’s only in the OneDrive cloud, the app goes to open it (so OneDrive gets a signal to temporarily download the real file for editing) and finds only a local placeholder (if a large file is not yet fully downloaded) so the app might display an error message. The only type of fully online file Photoshop works smoothly with is a Photoshop Cloud Document stored on Creative Cloud servers.

Running the apps online. The only way to run the apps online is to use the web app versions. For example, you can open a compatible web browser like Chrome and run Lightroom at lightroom.adobe.com, and you can run Photoshop at photoshop.adobe.com. However, the problem is that the web apps aren’t as fully featured as the desktop apps. Lightroom is the mobile/web version (not Lightroom Classic), and Photoshop is cut down like the iPad version, and both only work with files by uploading them to the cloud, not reading from your own storage. If you try the web-based apps and think they’re fine for your needs, you could upload all your photos to Creative Cloud servers and edit from there, if your plan has enough online storage.

Your question is marked Windows. For a Windows PC, a “big investment” is not necessary if the boot volume is in a slot and you can pull it out, like a standard NVMe SSD. Or if your PC has a second internal storage slot available. SSDs up to 4TB are becoming rather affordable, today I see under $250 for 4TB. You could buy an SSD bigger than what’s currently in your computer, plug it into the slot, and migrate your system to it. If this is at all possible with your PC, this would be the simplest solution.

Is it possible to install Lightroom Classic and Photoshop on an external drive and use the programs directly from that external drive?

Yes, you can install LrC and Photoshop on an external drive. In the Adobe Creative Cloud application, under Preferences/Apps/Install Location you can set it to any drive you want.

can I store the photos on the external drive?

Yes of course. When you import the photos, tell LrC to import them to the external drive. You can move existing photos to the external drive via these instructions (scroll down to Part 2 — Updating Folder Location for instructions).

I am confused by your usage of "external (online)"

Could I store them in an online storage space and still be able to use them in Lightroom and Photoshop?

No