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If you regularly work in programs like Adobe Premiere Pro, Final Cut Pro, and Adobe Photoshop, you’ve probably encountered errors relating to a 'scratch disk.' The most common error is Photoshop’s refusal to open, along with the message 'Could not initialize Photoshop because the scratch disks are full.'

• Thinking of ordering the base model but not sure whether to bump the storage to 512. It'll be a secondary computer so I don't need to fit everything in on it, just want to figure out how much actual space there is to play with.
• One way to start looking is to click the Apple menu, then select About This Mac. Click on the Storage tab, and System Information displays how much storage each attached drive contains. Below, you see that I have a lot of space available on my 2 TB Fusion Drive, a 4 TB backup drive that’s about 2/3 full, and an install disk that’s wide open.
• You can free up space on your Mac by manually deleting files and emptying your trash. You can also zip files or store them on iCloud to clear space on a Mac. Decluttering apps can help to quickly.

How much free storage should I have on my Mac? Before we review the storage requirements for applications and documents let’s discuss how much free space is needed on MacBook. If you ever wondered how a MacBook with 4 GB memory (RAM) can run applications that take 20GB on a disk the answer is that modern computers use the so-called virtual.

If you’ve stumbled on this page because you’ve experienced this issue, you’re in luck: we’re going to show you how to resolve your scratch disk problem easily and, as a bonus, keep your computer clean and performing at its best.

What is a scratch disk?

Before we highlight some solutions, it would be a good idea to have at least a general sense of what a scratch disk actually is. When you are using programs like Photoshop or Final Cut Pro, they require a working space called virtual memory or cache memory. This is where temporary project files are stored and accessed.

For this guide, we are focusing our laser sights on Photoshop. After all, it is the most common application. But rest assured that the info we cover will apply to most programs that rely on scratch drives.

Scratch disk is your hard drive space used by Photoshop as virtual memory when there is not enough RAM to complete a task. Photoshop allows you to assign several scratch disks: that way, it has more space at its disposal.

When working with large images and lots of layers, Photoshop is secretly chewing up your drive space by rapidly creating a mountain of project temp files.

It’s important to note that when you set up Photoshop, you will have the option to assign the scratch disks to the drive of your choice. We highly recommend not using your system drive unless you have no other alternatives.

Reasons behind “scratch disks are full” error

Temporary files are the most significant reason behind the “scratch disks are full” error. They usually mass up in your drive without leaving single evidence of their presence. If you have a habit of force-quitting Photoshop, you may have a lot of temporary files stored in your system. As Photoshop can’t fully close all projects after you quitted it so rapidly, it keeps such files on your machine.

Here are some other reasons that may cause the mentioned message:

• Lack of space in the drive where the scratch disk is located
• The partition of the disk being used by Photoshop is full
• Limited RAM allowed for the Photoshop

What to do when your scratch disks are full?

Next, we’ll explain how to clear out the scratch disk and fix the Photoshop issue on a Mac. If you’ve faced a problem on the Windows computer, follow the instructions below.

How to fix “scratch disks are full” error on Mac

Mac users receive a 'scratch disk full' message when Photoshop (or any of the other programs) has used up all the space on the hard drive that has been assigned as a scratch disk. This used-up space is temporary and separate from your actual project file.

The problem is that Photoshop doesn't always get rid of these temporary files when they aren't needed anymore, which is more like a permanent problem if the user can't find a solution.

So how to clear your scratch disks? Let's find out.

Important takeout: If your HD is full, Photoshop will display scratch disk errors.

1. Clear your Photoshop cache

Photoshop has an in-built solution for deleting specific Photoshop caches. When these pesky caches aren’t removed automatically by the program, they can grow and take up a lot of space on your scratch disk.

To use this tool, simply enter Photoshop in Mac and with an image open:

• Click the Edit menu button.
• Hover your mouse over 'purge' to reveal 4 different options.
• Undo, Clipboard, Histories, All. If an item is greyed out, that means it has already been deleted.
• Select the specific item you want to delete or select 'all' to delete all of your caches.
• You will be warned that the purge cannot be undone, so make sure you don’t need a previous version of one of your projects and then click OK.

A good way to keep Photoshop cache from piling up is by running regular disk cleanups. But here is a problem: the cache sits so deep in system folders (and their subfolders) that deleting it manually becomes a pain. A company called MacPaw produced a tool just for this purpose, CleanMyMac X. You've heard of similar tools, but that one actually pioneered Mac cleanup.

Here’s how you can schedule regular cleanings with CleanMyMac X:

1. Launch CleanMyMac X tool.
2. Click System Junk and press Scan.
3. Click Review Details to deselect the data you want to keep.
4. Hit Clean to clean up junk files.

Just let it do its thing. That way, you’ll never forget to clear Photoshop cache and tons of other system junk on your system.

You can download CleanMyMac X free version and see how it works.

How your Scratch drive is filling up, an example from Sketch

Along with Photoshop, Sketch is another app that keeps temporary versions of projects on your disk. And it eats up a whole lot: from 60 to 220 GB on average.

Each time you press Command + S, some space is wasted away from your Scratch drive. Say your file weighs 23 MB. Then, 7 temporary editions would increase that size to 161 MB. This problem hasn’t been widely known until recently, but, luckily, there is an automatic solution.

CleanMyMac’s System Junk module lists Documents’ Versions from Sketch and other similar apps. You can keep the final and the oldest version of a project and delete all revisions in-between. Voila, you’ve got free space again!

2. Delete your temp files

When it comes to wasting space on your scratch disk, the worst culprit is often Photoshop's own temp files. If Photoshop isn't going to get rid of them, I guess you’re going to have to do the job yourself.

To find them, you'll need to look for files that begin with 'pst' and then a string of numbers followed by the file extension '.tmp.' Search 'Photoshop Temp' with a space between the two words.

You can just search your scratch drive, but to make sure everything is found, rather perform the search on the entire computer. It may take a couple of minutes for the search to complete, so pop into the kitchen for a quick snack while you wait.

When you return, you should have a long list of files. If your work is saved and the program is closed, you can safely delete these files and watch as your scratch disk space is reclaimed.

3. Clear your disk space

If you don't have another drive or don't want to buy one, then it's time to do some spring cleaning. Look at the drive contents to see if you can delete anything you don't need. Is there storage space that can be cleared? Usually, there is, so go ahead and delete your old files and free up some space.

Alternatively, you can simply transfer files to external drives, DVDs, or cloud storage solutions like Dropbox and iCloud.

Take a look at our How to Clean Your Startup Disk (10 Ways). Inside we have lots of practical advice for macOS users who want a clean drive that performs well. Even if your scratch disk isn’t your startup drive, and we hope that is the case, there are many tips to help you spring clean like a pro.

Notice for macOS Sierra (and higher) users:Users of macOS Sierra might be aware that Apple has added new tools to 'help' manage storage space. If you navigate to Apple Menu > About This Mac > Storage tab, you will see the new Sierra bar graph.

If you click on 'manage,' you will be taken to the new tools. While there are some truly helpful elements, like using Optimized Storage to customize what email attachments download to your Mac, most of the tools move junk from one place to another place.

Because many of these processes are automatic, Sierra users might not be aware of what the OS is doing on their behalf. If it sounds like a good idea to have macOS deciding what files to send to iCloud and what iTunes videos to remove, go for it.

For everyone else, we’d recommend turning off these tools or at least making sure you understand them fully before turning them on.

It can be challenging to check and analyze all contents of your disk space. Luckily, some tools can provide a disk scan and can save up lots of space on your Mac. Apps notarized by Apple are best for this job. CleanMyMac X, the app I talked about earlier, has a Large & Old Files feature, which finds and removes massive files stored on your Mac.

4. Change your scratch disk

If the disk being used is nearly full, change the directory for a more spacious one. Then, restart Photoshop. You can change the Scratch Disk location by pressing the Command + Option when launching Photoshop. It can be a hassle, but if you keep an eye on the available space on your scratch disk, you can do something when space is becoming limited. It’s also worth noting that problems don't just occur when the drive is completely full, hard drives should ideally never be above 85% capacity. Pass that threshold, and problems will be just around the corner.

So, you've identified rapidly depleting free space on your Mac hard drive — now what? Well, it may be a good idea to change your scratch disk to another drive in your system (just not the system drive, as that is one drive you really don't want to slow down). If you don't have another drive, you could purchase one, with SSD being the best option for Mac OS X scratch disk purposes.

Follow these steps to change your scratch disk in Photoshop:

1. Click on the Photoshop menu.
2. Go to Preferences and then Scratch Disk.
3. Tick the checkbox to select or remove a drive as the scratch disk.
4. Click OK.
5. Restart Photoshop.

You can change the Scratch Disk location by pressing Command + Option when launching Photoshop.

5. Consider buying a new SSD

The scratch disk problem happens because of 2 simple reasons: lack of RAM and lack of HDD space. Both can be addressed if you buy a Thunderbolt SSD (solid-state drive) to use as your Scratch Disk. By today’s standards, 60 GBs should be enough.

Buy an external SSD to use as a Scratch Disk. 60 GB should be enough.

6. Follow the 15% rule

Not strictly a rule, but rather a common practice states that you should keep at least 10-15% of your disk space free at all times. If your HDD size is 256 GB, your lower limit is 25 GB. You’ll have enough room to render your Photoshop files, save multiple project copies, etc.

Loud fans noise is a sign your CPU is overloaded and approaching its carrying capacity.

7. Free up RAM in Terminal

When Photoshop gets paralyzed due to lack of RAM, there is a command you can run in Terminal.

1. Open the Terminal app (find it in the Launchpad).
2. Paste in: sudo purge
3. Then, enter your password.

At first, you may not see the difference, but you’ve just flushed your RAM, releasing all the files kept in virtual memory. There are a few more ways to free up RAM; check them out too.

You can also download CleanMyMac (get a free edition here) and use its Free UP RAM command.

1. Install the app and click on Maintenance.
2. Select Free Up RAM and click Run.

You can apply this trick anytime to unfreeze an app. Also, check out the other tools in the Maintenance section. They will help you take some load off your Mac’s memory.

8. Search for hidden files in your Photoshop folder

Some projects’ leftovers are invisible and yet take up lots of space. There is a shortcut combination to display hidden files in whatever folder you are in. So, open your main Photoshop folder and press Command + Shift + Period. If you find any greyed-out folders, check their weight.

To see hidden files in any folder, press Command+Shift+Period.

As you see, there are many methods to solve the “scratch disks are full” error. There is also one more way to reorganize data on your Mac and save up some space. Disk defragmentation gathers related items and lets you delete unneeded data as well as leftovers. Note that the latest macOS doesn’t need to be defragmented as Apple has provided it with in-built utilities, which automatically remove fragmented files. So, defragmentation may only work for you if your Mac’s running the OS version earlier than OS X 10.2.

How to clear the scratch disk on Windows

Free Up Disk Space On Macbook Air

If you are experiencing a “scratch disks are full” error on your Windows computer, freeing up space in the drive that accommodates the scratch disk may fix the problem. To do that, you need first to find out which drive Photoshop uses as a scratch disk.

1. Open Photoshop and go to Edit > Preferences.
2. Choose Scratch Disks.
3. Check which drive is used as a scratch disk.

The scratch disk should have at least 40GB of free space. If you see that it’s running out of space, access the drive and remove or transfer the largest files.

Another thing you may do to fix the error is clear out Photoshop temporary files. Just make sure you save your work first and close all Adobe apps. Then, go to the temp data folder
C:UsersYour UsernameAppDataLocalTemp. Look for the files that have “Photoshop Temp” in their names, highlight and remove them.

The 'Scratch Disk Is Full' error is fixed!

If you followed this guide, there is absolutely no reason why you should ever have to deal with the annoying 'scratch disk full' error again. Next time you want to create something amazing in Photoshop, you should experience something new - a Photoshop that runs so smoothly it practically purrs.

Whether you solve the problem yourself or let a great piece of software like CleanMyMac X do it for you, just make sure you clean up your scratch disk. Your Mac will thank you for it*.

*Not literally. That would be weird.

Frequently asked questions

Why does the “scratch disks are full” error may appear?

The number one reason for the “scratch disks are full” message is the lack of space in the drive where scratch disks are located. You can also run out of space in the partition of the disk allocated for Photoshop, which may also cause the above-mentioned error.

What are Photoshop temporary files?

Temporary files will appear if you don’t close Photoshop fully or open the Smart Object and don’t close them with the Smart Object layer. Photoshop temp files have a '.tmp' extension, so it’s easy to find them on your Mac.

How to fix the “scratch disks are full” issue?

One of the solutions is to change the scratch disk allocation. You may also need to clear the Photoshop cache and remove temporary files.

The Optimized Storage features of your Mac help you save storage space by storing your content in iCloud and making it available on demand:

• When storage space is needed, files, photos, movies, email attachments, and other files that you seldom use are stored in iCloud automatically.
• Each file stays right where you last saved it, and downloads when you open it.
• Files that you’ve used recently remain on your Mac, along with optimized versions of your photos.

If you haven't yet upgraded to macOS Sierra or later, learn about other ways to free up storage space.

Find out how much storage is available on your Mac

Choose Apple menu  > About This Mac, then click Storage. Each segment of the bar is an estimate of the storage space used by a category of files. Move your pointer over each segment for more detail.

Click the Manage button to open the Storage Management window, pictured below.

Manage storage on your Mac

The Storage Management window offers recommendations for optimizing your storage. If some recommendations are already turned on, you will see fewer recommendations.

Store in iCloud

Click the Store in iCloud button, then choose from these options:

• Desktop and Documents. Store all files from these two locations in iCloud Drive. When storage space is needed, only the files you recently opened are kept on your Mac, so that you can easily work offline. Files stored only in iCloud show a download icon , which you can double-click to download the original file. Learn more about this feature.
  
• Photos. Store all original, full-resolution photos and videos in iCloud Photos. When storage space is needed, only space-saving (optimized) versions of photos are kept on your Mac. To download the original photo or video, just open it.
  
• Messages. Store all messages and attachments in iCloud. When storage space is needed, only the messages and attachments you recently opened are kept on your Mac. Learn more about Messages in iCloud.

Storing files in iCloud uses the storage space in your iCloud storage plan. If you reach or exceed your iCloud storage limit, you can either buy more iCloud storage or make more iCloud storage available. iCloud storage starts at 50GB for $0.99 (USD) a month, and you can purchase additional storage directly from your Apple device. Learn more about prices in your region.

Optimize Storage

Click the Optimize button to save space by automatically removing watched movies and TV shows. When storage space is needed, movies or TV shows that you purchased from Apple and already watched are removed from your Mac. Click the download icon next to a movie or TV show to download it again.

Your Mac will also save space by keeping only recent email attachments on this Mac when storage space is needed. You can manually download any attachments at any time by opening the email or attachment, or saving the attachment to your Mac.

Optimizing storage for movies, TV shows, and email attachments doesn't require iCloud storage space.

Empty Trash Automatically

Freespace Social Media Platform

Empty Trash Automatically permanently deletes files that have been in the Trash for more than 30 days.

Reduce Clutter

Reduce Clutter helps you identify large files and files you might no longer need. Click the Review Files button, then choose any of the file categories in the sidebar, such as Applications, Documents, Music Creation, or Trash.

You can delete the files in some categories directly from this window. Other categories show the total storage space used by the files in each app. You can then open the app and decide whether to delete files from within it.

Learn how to redownload apps, music, movies, TV shows, and books.

Where to find the settings for each feature

How To Free Space On Mac System

The button for each recommendation in the Storage Management window affects one or more settings in other apps. You can also control those settings directly within each app.

• If you're using macOS Catalina or later, choose Apple menu  > System Preferences, click Apple ID, then select iCloud in the sidebar: Store in iCloud turns on the Optimize Mac Storage setting on the right. To turn off iCloud Drive entirely, deselect iCloud Drive.
• If you're using macOS Mojave or earlier, choose Apple menu > System Preferences, click iCloud, then click Options next to iCloud Drive. Store in iCloud turns on the Desktop & Documents Folders and Optimize Mac Storage settings.
• In Photos, choose Photos > Preferences, then click iCloud. Store in iCloud selects iCloud Photos and Optimize Mac Storage.
• In Messages, choose Messages > Preferences, then click iMessage. Store in iCloud selects Enable Messages in iCloud.

• If you're using macOS Catalina or later, open the Apple TV app, choose TV > Preferences from the menu bar, then click Files. Optimize Storage selects “Automatically delete watched movies and TV shows.”
• In you're using macOS Mojave or earlier, open iTunes, choose iTunes > Preferences from the menu bar, then click Advanced. Optimize Storage selects “Automatically delete watched movies and TV shows.”
• In Mail, choose Mail > Preferences from the menu bar, then click Accounts. In the Account Information section on the right, Optimize Storage sets the Download Attachments menu to either Recent or None.

Empty Trash Automatically: From the Finder, choose Finder > Preferences, then click Advanced. Empty Trash Automatically selects “Remove items from the Trash after 30 days.”

Other ways that macOS helps automatically save space

With macOS Sierra or later, your Mac automatically takes these additional steps to save storage space:

• Detects duplicate downloads in Safari, keeping only the most recent version of the download
• Reminds you to delete used app installers
• Removes old fonts, languages, and dictionaries that aren't being used
• Clears caches, logs, and other unnecessary data when storage space is needed

How to free up storage space manually

Even without using the Optimized Storage features described in this article, you can take other steps to make more storage space available:

• Music, movies, and other media can use a lot of storage space. Learn how to delete music, movies, and TV shows from your device.
• Delete other files that you no longer need by moving them to the Trash, then emptying the Trash. The Downloads folder is good place to look for files that you might no longer need.
• Move files to an external storage device.
• Compress files.
• Delete unneeded email: In the Mail app, choose Mailbox > Erase Junk Mail. If you no longer need the email in your Trash mailbox, choose Mailbox > Erase Deleted Items.

Learn more

• The Storage pane of About This Mac is the best way to determine the amount of storage space available on your Mac. Disk Utility and other apps might show storage categories such as Not Mounted, VM, Recovery, Other Volumes, Other, Free, or Purgeable. Don't rely on these categories to understand how to free up storage space or how much storage space is available for your data.
• When you duplicate a file on an APFS-formatted volume, that file doesn't use additional storage space on the volume. Deleting a duplicate file frees up only the space required by any data you might have added to the duplicate. If you no longer need any copies of the file, you can recover all of the storage space by deleting both the duplicate and the original file.
• If you're using a pro app and Optimize Mac Storage, learn how to make sure that your projects are always on your Mac and able to access their files.