Overview
Archive maintenance is a regularly scheduled task that runs on each backup destination. The purpose is to maintain archive integrity and optimize the size of the archives. When archive maintenance runs, it will:
- Check backup archives for corrupted files and repair any detected corruption.
- Prune file versions and remove deleted files according to the frequency and version settings.
- Purge files that are no longer selected for backup.
Archive maintenance in depth
The major operations that archive maintenance performs are defined and described below.
Prune
Pruning is the process that removes files and versions as defined by the frequency and version settings.
| Item | Description | |
| 1 | Block data files | Files stored in the archive as blocks of data. |
| 2 | Unused block data files | Pruning marks blocks as unused. Think of these blocks as "holes" that still take up space in the block data file until they are compacted. |
Compact
Compacting is the process that frees up space on the file system after pruning.
| Item | Description | |
| 1 | Unused block data files | Blocks marked as unused by the pruning process. |
| 2 | New block data file | The system rewrites the relevant block data file and omits the "holes" described in the previous section. The new block data file is smaller than the original. |
Validate and heal
Archive maintenance performs the critical task of validating the health of the backup archive and checking for data corruption.
| Item | Description | |
| 1 | Archive maintenance |
The process of archive maintenance. |
| 2 | Validation | If archive maintenance finds bad blocks of data, the destination self-heals the archive by re-requesting the affected data blocks from the source device. |
| 3 | Healing | The source device sends new blocks of data to heal the archive. |
Types of archive maintenance
The following table summarizes the differences between shallow and deep maintenance:
| Prunes files | Validates files and heals corruption | Verifies block checksums | Compacts archives | Resource intensive | Frequency | |
|---|---|---|---|---|---|---|
| Shallow maintenance | Yes | Yes | No | No | No | Every 60 days |
| Deep maintenance | Yes | Yes | Yes | Yes | Yes | Every 60 days |
Shallow maintenance
During shallow maintenance, the process will:
- Check for data corruption by making sure all files have valid versions and valid block lists.
- Prune file versions and deleted files based on the device's frequency and version settings.
- Prune deselected files and data excluded by file exclusions.
Shallow maintenance runs on an archive every 60 days. The shallow maintenance interval is not configurable for cloud destinations.
Deep maintenance
During deep maintenance, the process will:
- Check for data corruption by making sure all files have valid versions and valid block lists.
- Prune file versions and deleted files based on the device's frequency and version settings.
- Prune deselected files and data excluded by file exclusions.
- Validate block checksums for the entire archive.
- Compact archives to reclaim disk space.
Deep maintenance runs each time the last deep maintenance was more than 60 days ago, or if there is an error related to the archive.
Maintenance queue
All maintenance jobs get placed into a queue. This applies to shallow and deep maintenance jobs initiated by the user or the administrator.
There are two different maintenance queues—user and system:
- User: Archive maintenance initiated by a user, either by clicking Run maintenance in the CrashPlan app or following the steps below in the CrashPlan console. All jobs in the user queue undergo deep maintenance.
-
System: Archive maintenance initiated by the system according to the configured maintenance interval, or in response to a detected error in the archive.
Add a job to the archive maintenance queue
Follow these steps to manually add a job to the archive maintenance queue from the CrashPlan console:
- Open the CrashPlan console.
- Go to Administration > Environment > Devices.
- Select the device for which you want to start archive maintenance.
- From the device details, select the Archive Options icon
.
- Select Maintain Archive.
A message appears to inform you that running archive maintenance may cause the archive to become unavailable for restore or backup until maintenance finishes. - Click OK.
Your job is added to the queue.