How to use External Hard Drive for Photoshop (avoiding "scratch disk full" notifications)

[Cristina5FC6]

Hello everyone! I can't use Photoshop anymore because it says that the scratch disk is full. I have been researching and it is obvious that it's because I need more memory in my hard drive in order to use the program. I am planning to buy an external hard drive in order to solve it; nonetheless, I am worried that Photoshop won't recognize the hard drive like it has happened to me before. Is this because I should always reformat it for me to finally use it in Photoshop? Or is buying a hard drive for this purpose not the correct solution?

I'm looking forward to your responses!

[JJMack · Accepted solution]

It look like your Mac  Photoshop is not supporting your external disk for scratch space.  On Windows Photoshop supports scratch one external storage like USB3 hard disk.  Photoshop does not support USB  Flash drives.  Windows regards these as removable storage.  Photoshop most likely does not think movable storage is appropriate for scratch space.

If you add a external hard disk or SSD   you mac OS will see it as perminate storage and Photoshop will show they are available to be configured for scratch.  You should not include your boot disk,   When I start PS 8GB of scratch space is used right away. You system will mot rune if your boot disk fills.  You really need to free up space yous system disk.

I have seen PS use 100GB of scratch on my system  for some batch joobs

[Cristina5FC6]

So buying an external hard drive or SSD for Mac and then reformatting it would be the best option? I have deleted a lot of applications as well as used iCloud and Photoshop still notifies me scratch disk is full. 

[Kevin Stohlmeyer]

Yes. It has to be formatted properly for the Mac OS (Mojave, Catalina or Big Sur) to recognize it and allow permissions properly.

[Molly Mortimer]

Is there a way to format my external hard drive without wiping it? I've been using it for backups but it still has LOTS of free space

[D Fosse]

No. That's what formatting does.

Copy everything off the drive, then copy it back.

[Conrad_C]

I use these steps:

1. Make sure there is at least one other complete backup of the data, and make sure it is fully up-to-date. Because I regularly maintain at least two up-to-date backups of files I can’t afford to lose, that’s already set up. The reason I maintain two backups is that I go by the industry rule “one backup is not really a backup” (to insure against the failure of your only backup).

2. Format the backup drive.

3. Restore the formatted drive from the other identical up-to-date backup drive.

If you don’t have a second backup, you could restore the reformatted backup from the original data you are backing up. But of course that means you will be operating for a short time without a backup.