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Understanding And Troubleshooting Archive Maintenance

Applies to:
  • CrashPlan for Home
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This article is intended for CrashPlan for Home users. For Code42 CrashPlan and CrashPlan for Small Business documentation, read this page on our enterprise support site.


The purpose of archive maintenance is to maintain the integrity of your backup, and to reduce the size of the archives. This is accomplished by:

  • Checking backup archives for corrupted files and repairing any detected corruption
  • Pruning file versions and removing deleted files according to the frequency and version settings
  • Purging files that are no longer selected for backup

All backup destination types (cloud, computer, and folder) perform archive maintenance.

Troubleshooting archive maintenance

The process of archive maintenance can have several effects on your backup. This section describes those effects as well as how to start archive maintenance.

Why is my backup not running?

You may receive a backup status report informing you that you have not backed up in several days, or you may notice an "Unable to backup: Archive is being maintained" message in the CrashPlan app. When archive maintenance runs on your backup archive, all backup activity stops until maintenance has completed. The amount of time required to run maintenance varies based on the size of your archive. Your backups will resume as soon as maintenance completes.

Why can't I restore files?

During the process of archive maintenance, access to the archive is restricted and restores from the CrashPlan app are disabled. If you begin a restore from the CrashPlan app while maintenance is running, the restore screen displays "Restore Pending." Once maintenance has completed, restores from the CrashPlan app are enabled and any pending restores will begin.

If you are trying to restore and cannot find a particular file, there may be an issue with your local CrashPlan cache files, or the file may have been removed due to corruption.

What happened to my files?

As part of archive maintenance, CrashPlan scans files for corruption. When it detects a corrupt file, CrashPlan removes the file from the archive and re-requests the file for backup. If the original file isn't available on the source machine when re-requested, the corrupted file is not recoverable.

How can I schedule archive maintenance?

CrashPlan for Home only

Each backup destination has its own archive maintenance interval that applies to all archives within that destination.

Computer destinations are other computers that can be used as backup destinations. For example, if you have both a desktop and a laptop, you could use the desktop as a destination for the laptop, and vice versa.

Local folder destinations can be any folder or directory located on any disk that is physically mounted on a device running the CrashPlan app. However, local folder destinations are generally located on an external hard drive, USB drive, or other large capacity external storage device.

Maintenance Scheduling
Local folder backups cannot be scheduled separately from other inbound computer backups. If a computer is backing up to a folder location and also receiving backups from another computer, maintenance for both backups will run on the same schedule.

The maintenance interval is not configurable for CrashPlan Central. For computer-to-computer backup, perform the steps below for the destination computer. For local folder backups, perform these steps for the source computer.

To configure the maintenance interval from the CrashPlan app:

  1. Open the CrashPlan app.
  2. Go to Settings > General > Inbound backup from other computers.
  3. Change the settings for Perform shallow maintenance and Perform deep maintenance.

Archive maintenance in depth

The major operations that archive maintenance performs are defined and described in detail in this section.

Starting archive maintenance

To immediately update your backup archive with file selection or retention policy changes (such as how many versions to keep and how long to keep deleted files), follow these steps to start archive maintenance:

  1. Open the CrashPlan app.
  2. Go to Destinations.
  3. Select the destination type (for example, Cloud).
  4. Select the name of the destination for which you want to start maintenance.
  5. Click Compact.


Pruning refers to the process by which CrashPlan removes files and versions of files that are no longer needed as defined by the frequency and version settings. The relevant blocks of data are marked as unused. These blocks can be thought of as “holes” that are still taking up space until the compacting process is done.


Compacting is the process that actually opens more free space on the destination after pruning removes versions and files from an archive. During the compacting process, the destination rebuilds the archive and omits the “holes” described in the previous section. Thus, your archive does not decrease in size until the compacting process completes.

Validation and healing

Archive maintenance performs the critical task of validating the health of your backup archive and checks for data corruption. If bad blocks of data are found during archive maintenance, the destination self-heals the archive by re-requesting the affected data blocks from the source device.

Types of archive maintenance

Shallow maintenance

During shallow maintenance, the destination:

  • Checks for data corruption by making sure all files have valid versions and valid block lists
  • Prunes file versions and deleted files beyond what is allowed by the device's configured frequency and version settings
  • Prunes files that were deselected or that were newly excluded by file exclusions

Shallow maintenance runs on CrashPlan Central archives every 7 days. Computer and local folder destinations run shallow maintenance according to the configured schedule.

Deep maintenance

During deep maintenance, the destination:

  • Checks for data corruption by making sure all files have valid versions and valid block lists
  • Prunes file versions and deleted files beyond what is allowed by the device's configured frequency and version settings
  • Prunes files that were deselected or that were newly excluded by file exclusions
  • Validates block checksums for the entire archive
  • Compacts archives to reclaim disk space

Deep maintenance runs on an archive every time the last deep maintenance was more than 28 days ago, if there is an error related to the archive, or was initiated by clicking the Compact button in the CrashPlan app. The deep maintenance interval is not configurable for CrashPlan Central, but runs for computer and local folder destinations according to the configured schedule.

Summary table

The following tables summarizes the differences between shallow and deep maintenance.

Prunes files Checks for file corruption Verifies block checksums Compacts archives Resource intensive Default interval
Shallow maintenance Yes Yes No No No 7 day
Deep maintenance Yes Yes Yes Yes Yes 28 days