Storage for Lightroom Classic

I plan on buying a 4TB external drive which would last me a long time before needing upgrade. It is much less expensive than buying more space from Apple. I was more concerned with having enough overall space on the Macbook to keep from running out since it cannot be upgraded.

By @PoppyFromNC

I’ve been doing something similar for years. I have a Mac with 1TB internal storage where my Lightroom Classic catalog folder is stored, and a 4TB external volume where all of the original photos and videos are stored. Lightroom Classic has no problem tracking photos on any number of external volumes; each of them is listed at the top level of the Folders panel.

I try to keep 100–200GB free, but I do run low on internal storage from time to time. For me, it’s usually because of the client projects that I keep on the laptop while working on them. They grow as I build and render more project files, and when a project is finished, I archive it off to an external volume and get back that internal space.

The other reasons I run low on space are some you might want to keep in mind.

I said that I store the Lightroom Classic catalog on my internal storage. The catalog is a few GB in size, but grows slowly. The previews associated with the catalog can grow quickly, and can reach 30GB or more. Fortunately, previews are automatically regenerated so sometimes I throw out the …Previews.lrdata file to get that space back, knowing the previews file will grow again. If your external volume has several hundred GB of free space, it might be better to store the catalog there and not worry about the size of the previews file.

Large amounts of free space can also disappear for the following reasons, see if any of them apply to you and would affect how much free space you need:

• Photoshop scratch files. If the Photoshop scratch disk is set to the internal volume, large Photoshop files can create large temporary scratch files, possibly a few hundred MB depending. 
• Time Machine local snapshots. If you use Time Machine, and the backup volume is not connected, Time Machine can accumulate local backup snapshots. After the backup volume is connected and the next backup happens, those local snapshots get offloaded to the external backup, and the space frees up. (In a pinch, you can view and delete each volume’s local snapshots in Apple Disk Utility.)
• iOS device backups. If you have an iPhone or iPad, and you back it up on your Mac, those device backups can take up a lot of space. 
• Other cache files. If you use applications such as Adobe Premiere Pro and Adobe After Effects or other intensive media editors, they may want to create large local caches to enhance performance, up to several hundred GB depending on the projects. Similar to Photoshop, I have to assign those Media Cache Files to an external because they will take up too much space on internal storage. 
• Virtual memory swap. If an app happens to need so much memory that the request can’t be handled by real memory or memory compression, macOS will start to use storage space for temporary swap files. You can watch this in Activity Monitor, Memory tab.

Depending on what I’m doing, in one typical day free space can go down and then back up by many GB, depending on which apps are allocating or releasing large temporary files at that time.

My last two Macs have been OK with 1TB of internal storage, but next time I might let myself spend more for 2TB. If you do not do a lot of intensive work on the laptop other than amateur photography, maybe 1TB is just fine.