What should you back up?

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To help protect your data from loss, CrashPlan uses backup to automatically collect and store your files. A backup set is a set of files you have selected to back up.  If you have questions about what to include in your backup set, this article provides tips and advice for ensuring you back up the files you need.


This article assumes you have permission to change your backup file selection. Your administrator may prevent editing of the backup file selection.

Which files should you back up?

The short answer is, "Back up the files that matter to you." The CrashPlan app is designed to back up and restore your user files.


User files

The CrashPlan app is designed to protect your user files. In other words, the files you create, edit, and access that allow you to get your job done. They also include certain files created by applications based on your information and settings in those programs.

  • Examples: Documents, spreadsheets, photos, videos, Outlook messages, web browser bookmarks
  • Location: Typically stored in a User directory or Home folder

Don't back up operating system and application files

The CrashPlan app isn't designed to back up system and application files, don't add these files to your backup selection. Doing so could cause issues with the priority and status of other files you want backed up. Additionally, since the CrashPlan app isn't designed to download your operating system or applications, there is no advantage to backing up these types of files.

System files

These are files that your device needs to work correctly. They may be a part of your operating system, a third-party device driver, or another source. Typically, you don't interact with these files directly.

Application folders

These folders contain the files that allow various applications—like your email, word processor, and web browser programs—to work correctly. Like system files, you don't typically interact with these files directly.

What happens if the entire hard drive is selected?

If you select your entire hard drive as your backup set, including system and application files, these files could prevent your business files from backing up efficiently.

As part of its normal operation, your device creates new system and application files, which are small. Because the CrashPlan app prioritizes the to-do list based on size and creation date, the system files are backed up before other files in your backup selection.

Some symptoms you might see if the CrashPlan app backs up system or application files:

  • Time to complete backup selection increases, sometimes by many days.
  • Backup never reaches 100%.
  • Backup status is incorrectly reported.
  • No files are displayed on the Restore Files or Get Files screen.

 Safely deselecting your hard drive

If your entire hard drive is already selected for backup, it's possible to deselect it without losing your existing backup.

  1. Open the CrashPlan app and go to Manage files
  2. Uncheck the box next to:
    • Windows: C:
    • Mac: / or Macintosh HD 
  3. Verify any external drives you want backed up are selected. 
  4. Navigate to the folders and files you want backed up. User files are typically stored in a User directory or Home folder. 
  5. Select the check box next to the files and folders you want backed up. 

CrashPlan will synchronize with your existing files, keeping the user files you've selected and purging any unnecessary system or application files. 

Where to start

Your administrator may configure the CrashPlan app to begin backing up immediately after you sign in to a device for the first time. However, if your backup isn't already configured, then the CrashPlan app prompts you to create your first backup set. If prompted,

  • Click Manage Files and then add files to your backup.

Always add your User folder. This a great folder to start with because your business files and settings are typically saved here. This includes files you create or add, like documents and photos, as well as your customized settings for various applications.

 Viewing your backup selection

In the CrashPlan app, click Manage Files to quickly see what's included in your backup selection.

For example, the Marvin folder includes this user's Desktop, Documents, Downloads, Movies, Music, and Pictures folders, as shown below.


Additionally, although typically "hidden", this folder contains the user's Library, which houses user information like application preferences, bookmarks, and fonts1. This is similar to the AppData folder in the User folder on devices running Windows. Even though the Library and AppData folders are usually "hidden" in your file browser, the CrashPlan app knows to back them up when the User or Home folder is selected.

1If you have installed any non-standard fonts at the system level, consider also backing up those files. The Font folder is located under the System folder on Mac or the Windows folder on Windows. 

Additional considerations

If you have questions about backing up a particular type of file, our Backup guide is a great place to start. A few common considerations are listed below.

External drive

If you have an external drive that you want to back up, you can update your file selection to include this drive. If you want to back up the external drive on a different schedule than your local files, you can create backup sets to manage the file selections separately.

Deselect files

This default backup set often covers the majority of what should be included in your back up set. If you are concerned about the size of your backup set, you may choose to selectively delete folders or individual files from your backup selection. You can also choose to delete specified file types from this set, regardless of where they are stored.

Time Machine

The CrashPlan app and Time Machine complement each other well and they can be used on the same device, side-by-side, backing up your live data. However, for technical and practical reasons, you shouldn't try to integrate the two. Instead:

  • If you only use Time Machine for backup, then exclude the entire drive from your backup set.
  • If you use Time Machine for backup and storage, then exclude the Backups.backupdb folder that contains your Time Machine backup from your CrashPlan app backup set.

Virtual Machines and boot partitions

Backing up virtual machines (VMs) or separate boot partitions are special cases that may require specific settings. See our guide to backing up virtual machines and special boot partitions for more information.

User permissions requirement (Windows)

In the default Windows installation (installing the CrashPlan app for everyone on the device), the CrashPlan app relies on the system user's read/write permissions to access your files. However, there are some files or folders the system user may not have permission to access. If you need to back up these files or folders, follow our tutorial to add the system user to the permissions list.

Still unsure?

Contact your administrator or contact technical support for additional guidance.

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