Skip to main content

This article applies to Code42 for Enterprise version 4.

Other available versions:

Version 6 | Version 5icon.qnmark.png

Code42 Support

CrashPlan and OS X metadata

This article applies to Code42 for Enterprise version 4.

Other available versions:

Version 6 | Version 5icon.qnmark.png


This article explores how CrashPlan and OS X use metadata to determine which files to exclude from your backup, and demonstrates how to change the metadata of a file so that it will be included in your backup.

What is metadata?

Metadata is data about data. A good example of metadata is the file creation date. When saving a file on your hard drive, your computer automatically records information about when the file was created. You don't manually say, “I created this on 3/19/99 at 12:00pm.” Your computer does it for you.

iTunes movie rental example

iTunes movie rentals are a great example of how metadata works with CrashPlan backups. If you have included your iTunes folder in your backup selection, then any changes to that folder, such as adding or removing files or creating or changing playlists, are automatically backed up to CrashPlan.

What About iTunes Movie Rentals?

A movie rental is a large file (usually 1 - 2 GB) that is automatically deleted after 24 hours. If you back it up, it won't play after 24 hours anyway. Basically, it's a complete waste of time to back up.

That's where metadata comes in. To avoid unnecessary backups, iTunes attaches metadata to each movie rental file that says, “Don't back this up.” CrashPlan is smart enough to note the request and ignore the file.

Any program on OS X can tag any file with the “Don't back this up” metadata. Generally, programs like iTunes know best when it comes to identifying which files should be backed up and which ones shouldn't. However, there may be times when you want to override the existing metadata in order to include a file for back up that is excluded by default. Read on to learn how.

What is being excluded?

Finding out what is being excluded from your backup based on metadata is easy, but requires interaction with the OS X command line. To find out which files are being excluded on your system, enter the following line in Terminal:
sudo mdfind "com_apple_backup_excludeItem = ''"

This command queries Spotlight to tell you every file that has the metadata “com_apple_backup_excludeItem”, which means, “Don't back this up.”

Remove exclusion metadata

To remove exclusion metadata from a file on OS X, open Terminal and enter the following command, replacing "file path" with the full path to your desired file (e.g., "/Users/Joseph/my file.iso").
xattr -d "file path"

To confirm that exclusion metadata has been removed, enter the following command:
sudo mdfind "com_apple_backup_excludeItem = ''"

If the above removal command succeeded, the name of your file will not be included in the list of excluded items.


For this example, let's assume you see a file named windows image.vmdk in the list of metadata backup exclusions, and that you do actually want to make sure that file is backed up by CrashPlan. To change the metadata on the file and enable back up, enter the following in Terminal:
xattr -d "/Users/Joseph/windows image.vmdk"

To confirm that the file has been removed from the excluded item list, you can enter the following in Terminal:
sudo mdfind "com_apple_backup_excludeItem = ''"

This command lists all excluded items. Because the file you removed, windows image.vmdk, is not listed, it will be backed up.

Now CrashPlan knows to back up the windows image.vmdk file. In fact, other backup software will also note that change, so if you happen to also be using Time Machine, Time Machine would start backing up the file as well.

Considerations with removing exclusion metadata

It is wise to make sure your critical files are not marked with metadata that says, “Don't back this up,” but it's also important to use caution when changing metadata on files. Most of the time, metadata to exclude files from backup is there for a reason (the files may be unnecessary, temporary in nature, or large system files that don't back up well).

Make sure you understand the implications of changing the backup metadata not only for CrashPlan, but for any other software that depends on metadata.

Add exclusion metadata

Adding metadata to stop files from being backing up isn't necessary; if you no longer wish to back up a file, simply remove it from your backup file selection.