Photoshop 7.0 "Scratch Disk Is Full" Error — Quick Fix Guide

By the Photoshop 7.0 Hub editorial team · Updated May 17, 2026 · 10-minute read

What Is a Scratch Disk?

When Photoshop 7.0 needs more RAM than the operating system is giving it, it uses a portion of the hard disk as overflow memory. This area is called the scratch disk. Photoshop writes a temporary file to it (named something like ~PST0001.tmp on Windows or Photoshop Temp NNNN on Mac), and reads/writes that file as you edit.

Because Photoshop 7.0 is a 32-bit application limited to 2 GB of RAM, the scratch disk is used heavily — every history state, every layer, every undo. A typical session can write 5–10 GB to the scratch disk even when the open document is only a few hundred MB.

"Scratch disk is full" means Photoshop tried to grow its temp file and the disk it lives on has no free space left.

Emergency Fix — When You See the Error Right Now

1. Save your work if you can. If Photoshop is still responsive, Ctrl+Shift+S immediately to save as PSD to a different drive that has free space.
2. Close any other open documents you do not need right now. Each open document holds part of the scratch.
3. Reduce History States. Edit → Preferences → General → set History States to 5 (default is 20). Each state consumes scratch space.
4. Purge. Edit → Purge → All. This frees the History, Clipboard, Undo, and Pattern caches. Photoshop may pause for a few seconds.
5. If still failing, quit Photoshop. Photoshop deletes its temp files on a clean quit.

Permanent Fix — Move Scratch Disk to a Larger Drive

By default, Photoshop 7.0 uses the drive Windows is installed on (usually C:) as the scratch disk. If C: is small or near-full, moving the scratch disk to a different drive solves the problem permanently.

1. Open Photoshop. If it crashes on launch with the scratch-full error, hold Ctrl+Alt while double-clicking the Photoshop shortcut — a scratch-disk-selection dialog appears before Photoshop fully loads.
2. Edit → Preferences → Plug-Ins & Scratch Disks.
3. Four scratch-disk slots are shown. Photoshop uses them in order — if the first fills up, it spills to the second, then the third, then the fourth.
4. Pick the drive with the most free space as First. Pick a second drive as Second (Photoshop will spill there if the first fills).
5. Click OK. Photoshop must restart to apply the change.

Use an SSD for the Scratch Disk

The scratch disk is read and written constantly. Its speed has a direct impact on Photoshop's responsiveness, especially on large files. The choice that matters:

• NVMe SSD (best) — 3,500 MB/s read, 3,000 MB/s write. Photoshop feels nearly instantaneous.
• SATA SSD (excellent) — 550 MB/s read, 500 MB/s write. Still vastly better than a hard drive.
• HDD (acceptable) — 100–150 MB/s. Photoshop is usable but slow on large files.
• External USB 2.0 drive (avoid) — 30 MB/s. Photoshop becomes painful.

If your computer has an SSD and an HDD, point Photoshop's first scratch at the SSD. The SSD does not have to be where Windows lives.

Dedicate a Scratch Partition (Advanced)

For heavy users, the optimal setup is a separate physical SSD (or a dedicated partition) used exclusively as Photoshop scratch. Reasons:

• The scratch disk's contents are temporary — they survive only for the duration of a Photoshop session. No need to back up.
• A scratch-only partition cannot become full from other activities.
• Reads/writes from other applications do not compete with Photoshop's scratch I/O.

To create a dedicated scratch partition:

1. Right-click Start → Disk Management.
2. Pick a drive with at least 20 GB of free unallocated space.
3. Create a new simple volume, format as NTFS, label as "Scratch".
4. Point Photoshop's first scratch at this new drive letter.

How Much Free Space Does Photoshop 7.0 Actually Need?

Adobe's guideline: at least 20 GB of free scratch-disk space when working on typical files. The real-world rule of thumb:

• Working on JPEGs up to 24 MP: 5 GB free is enough.
• Working on 50–100 MP files or large PSDs with 10+ layers: 20 GB free.
• Working on 100+ MP files, panoramas, or 200+ layer composites: 50 GB free, on an SSD.

If the scratch disk drops below 1 GB free, Photoshop will refuse to perform many operations and start showing the error.

Reduce How Much Scratch Photoshop Uses

Some workflow changes that significantly reduce scratch consumption:

Reduce History States

Edit → Preferences → General → History States. Default is 20. Reduce to 10 if you work with very large files. Each state stores the entire image's state, so 20 states on a 200 MB document means up to 4 GB of scratch.

Lower the Memory Usage percentage

Edit → Preferences → Memory & Image Cache. Set Memory Usage to around 70%. Higher values force Photoshop to use the scratch sooner; lower values keep more in RAM. 70% is the sweet spot for most systems.

Flatten unused layers

If your document has dozens of layers that are no longer being edited, merge them into one. Ctrl+E merges the active layer down; Layer → Flatten Image merges everything. Each removed layer reduces scratch usage proportionally.

Close other open documents

Photoshop maintains scratch space for every open document, not just the active one. If you have 8 PSDs open at once, close the ones you are not actively editing.

Reduce the image-cache levels

Edit → Preferences → Memory & Image Cache → Cache Levels. Default is 6. Reduce to 4 if scratch is tight. Higher cache levels speed up zoom-out redraws but consume scratch.

Clear Old Photoshop Temp Files Manually

When Photoshop crashes (rather than quitting cleanly), it leaves its scratch temp file behind. Over time these accumulate and consume disk space. To clean them up:

Windows

1. Make sure Photoshop is closed.
2. Open File Explorer. In the address bar paste: %TEMP% and press Enter.
3. Look for files starting with ~PST (e.g., ~PST0001.tmp, ~PST0002.tmp). These are leftover Photoshop scratch files.
4. Select all ~PST*.tmp files and delete. Some may be locked — close any other Adobe programs and try again.
5. Empty the Recycle Bin.

macOS

1. Close Photoshop.
2. Finder → Go → Go to Folder → paste: /private/var/folders/ → enter.
3. Search for files named "Photoshop Temp" within the subfolders. Delete them.
4. Empty Trash.

On both systems, a Windows or Mac reboot also clears all leftover temp files automatically.

Preventing the Error in the Future

1. Always have at least 10 GB free on your scratch drive. Treat this as non-negotiable.
2. Use an SSD as the first scratch disk. Performance benefit is large and SSDs handle the constant read/write better than HDDs.
3. Configure a second scratch slot as a fallback. If the first fills, Photoshop spills over instead of erroring.
4. Set a calendar reminder to clear %TEMP% monthly. Over a year, leftover scratch files can occupy 50+ GB.

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