Photoshop not using scratch disks

[MADPResearch]

Hello,

I am working on a large file (10000 mm x ~8000 mm) that was imported from an orthographic aerial drone mapping project. I have trimmed out all the "fat" from the image and now want to move one section, but it is saying "scratch disks are full". Yet, when I look at the drives in File Explorer, the four drives I have as scratch disks are virtually empty. I have devoted about 20 TB of drive space to scratch disks, so there is NO WAY that a single file should be filling that up. How do I fix this issue?

Computer specs: Windows 11, Threadripper 3970x 32 core, 256 GB DDR 3133 hz DDR4 RAM, AMD Radeon RX 6900 XT. 

Thanks

[davescm]

A couple of questions:

First, what is the image size in pixels and how many layers are you using? The physical image size in mm is meaningless as it could be 100ppi or 1000ppi which would give very different pixel sizes.

Second, how much available space is there on the first disk you have allocated to scratch? Ideally that should not be your system disk but a fast internal drive. Using the system disk competes with Windows own disk use. You could be hitting an issue using a function which requires a single temp file which cannot be split across disks.

You can see the scratch disk files using file explorer as you work with Photoshop open, but they are deleted when Photoshop closes. So check them as you work, to see if you can see where the problem lies.

You can reduce scratch space by reducing the number of history states which use up enormous amounts of space with large files.
 
Dave

[MADPResearch]

Hello Dave, 

Thanks for the speedy reply. The file size is 500 p/i, hence why I am cutting all the white space out of the imported image via the lasoo tool. 

The first scratch that it's writing to is a 2TB NVMe drive that's virtually empty (It has about 1.8TB free). The most that the drive gets filled is only about 50%.

I'll check the number of history states, but I would have thought I had enough disk space available.

Thanks

[Kevin Stohlmeyer]

@MADPResearch that is a redicuously large file. Even without doing anything a file 10000 x 8000 mm at 500 ppi is over 90 GB in size base for a blank document with no pixel data. You can check your document file size using the lower left window to calculate the open file size. It's reasonable to assume that even with your scratch disks you are exceeding your available computer's resources. 

[MADPResearch]

Hello Kevin,

Hahaha, yeah, it's massive. At that size, it's still only 1/4 of the actual size of the image that I have input. The image is an aerial map of a river valley in the Alberta mountains that I am mapping the geology in. Due to the steepness of the river banks, I can't easily or safely reach the rock outcrop in most regions. Instead, I use a drone to map the rock at 1 pixel = ~1 mm. That way I can look at the rock in decent enough resolution to see what each rock type is and any structures in them. Unfortunately, I don't have many options to make it smaller and still see the details. It's just odd because the file image I am importing is only 450 MB, and I have done images that were 20 GB and 250 m x 150 m at print size without issue before. I have been having issues with Illustrator recently as well, so I am wondering if it may be an issue with a recent update.

[davescm]

Yes, you are going to need a lot of scratch disk space. At 500ppi, your 10,000 x 8000mm file has 196850 pixels x 157,480 pixels = 30G pixels. For an 8 bit image that takes 90G bytes and for a 16 bit image 180GB per layer. Multiple layers expand that considerably.

Each history state stores the entire image so it would not take long to fill up the scratch disk space on a disk.

Dave

[davescm]

'the file image I am importing is only 450 MB'

The file on a disk is compressed and compression algorithms can be very efficient.. When opened in RAM it is uncompressed - each pixel using 3 bytes for a single layer 8 bit/channel RGB image and 6 bytes for a single layer 16 bit/channel image. 

[MADPResearch]

Hi Dave, 

Thanks, I'll see if I can change the primary scratch disk to the 12TB hard drive and just have to accept it's going to be a bit slower.

[davescm]

That may avoid Photoshop throwing the error when trying to create a single file for an operation. Let us know how it goes.
Dave