Data Integrity Check in HBS 3
- Data Integrity Check in HBS 3
- How Data Integrity Check Works
- Running Data Integrity Checks
- Data Corruption Repair
- Schedule Conflict Policies
Data Integrity Check in HBS 3
This feature is available in HBS 3 v16 and later.
Data Integrity Check is a feature in HBS 3 that analyzes your backups and attempts to repair any corrupted data.
Due to the dynamic nature of most files, there are many opportunities for your data to become corrupted. This corruption might be intentional or unintentional. Intentional corruption might be caused by malware or human actors. Unintentional corruption might be caused by software, hardware, power, or network failures.
To reduce the chances of losing your data, QNAP recommends adopting a 3-2-1 backup strategy (Keep three total copies of your data, Store two copies on different media, Store one copy off-site). Additionally, you can use data integrity checks for extra security.
How Data Integrity Check Works
Data integrity checks compare your backed up data to the original files and attempt to determine if any corruption has occurred. HBS 3 offers two types of data integrity checks: quick check and content check.
Data integrity checks require significant system resources and may take a long time to complete. For the best processing speed, QNAP recommends using an x86-based device with SSDs.
| Feature | Quick Check | Content Check | |
|---|---|---|---|
| Method | Compares the existence, size, modification time, and/or hash value of each file | Uses one of the following methods:
| |
| Supported Jobs | Created in HBS 3 v16 or Later | All backup jobs except NAS-to-NAS jobs with QuDedup disabled | All backup jobs Note: For NAS-to-NAS jobs, if the destination NAS runs HBS 3 v15 or earlier, only jobs with QuDedup enabled are supported. |
| Created in HBS 3 v15 or Earlier | All backup jobs except NAS-to-NAS jobs with QuDedup disabled | None | |
| Supported Cloud Destinations | HBS 3 currently supports all cloud destinations except the following:
| ||
Quick Check
Quick checks require fewer system and network resources than content checks, while still ensuring a basic level of data integrity.
| NAS-to-NAS Backup Jobs | NAS-to-Cloud Backup Jobs | |
|---|---|---|
| QuDedup Disabled | QuDedup Enabled | - |
| Unavailable | The following metadata are compared for each file:
| The following metadata are compared for each file:
|
For jobs where client-side encryption is enabled, hash values are also recorded and compared.
Content Check
Content checks provide a more thorough analysis of data integrity than quick checks, but may require significantly more system and network resources to perform.
Because data can still be altered without changing the file size or modification time, comparing hash values or file contents is a more reliable method to detect data corruption.
To perform content checks, you must enable Content Check from the Data Integrity Check screen when configuring the backup job. For details, see the Hybrid Backup Sync documentation.
| NAS-to-NAS Backup Jobs | NAS-to-Cloud Backup Jobs | |
|---|---|---|
| The following metadata are compared for each file:
Note: If the HBS 3 version on the destination NAS does not support data integrity checks:
| Files are downloaded temporarily and hash values are calculated for comparison. Important: This may result in additional fees from your cloud service provider. | |
After you enable Content Check for the first time, HBS 3 will continue to record MD5 hash values even if you disable it later.
Running Data Integrity Checks
You can run data integrity checks manually, or configure scheduled checks when creating a backup job.
| Frequency | Quick Check | Content Check |
|---|---|---|
| Manual checks |
|
Note: You must enable Content Check in the backup job configuration in order to run a content check. |
| Scheduled checks | For details on configuring quick check and content check schedules, see the Hybrid Backup Sync documentation. | |
Data Corruption Repair
When performing a data integrity check, if HBS 3 finds that any files have been corrupted, it will attempt to repair those files automatically at the end of the check.
Automatic repair is unavailable for NAS-to-NAS backup jobs with QuDedup disabled.
If version management is enabled for a backup job, HBS 3 also checks the data integrity of all backup versions where hash values were previously recorded. However, only data corruptions found in backup versions that are identical to the latest version can be repaired.
For example, suppose the most up-to-date backup is at version 5. If a file was updated only once in its entire history in backup version 3, and HBS 3 finds that version 2 of the file has been corrupted, HBS 3 would only be able to report the corruption but not repair the file. However, if HBS 3 finds that backup version 4 of the file has been corrupted, it would be able to repair the file because the file has remained unchanged between versions 4 and 5.
Schedule Conflict Policies
HBS 3 resolves schedule conflicts between a backup job and its data integrity check or data corruption repair depending on different circumstances.
Data Integrity Check
-
While a backup job is running, HBS 3 skips all manual and scheduled checks.
-
If a backup job is scheduled to run during a data integrity check, the data integrity check pauses and resumes after the backup job finishes.
-
If a quick check and a content check are both scheduled to run at the same time, only the content check will run.
Data Corruption Repair
If a backup job is scheduled to run during a repair session, their schedules are resolved according to the job type:
-
Backup jobs with QuDedup enabled: The backup job is skipped until its next scheduled run.
- Cloud jobs with QuDedup disabled: The repair is paused and resumes after the backup job finishes.
