Backup4all can use the USN journal to get a faster detection of the modified source files. The USN Journal (Update Sequence Number Journal), or Change Journal, is a feature of NTFS which maintains a record of changes made to the volume.
On this page:
- How to activate/deactivate the “Smart file scanning mode” option?
- When the “Smart file scanning mode” applies?
- How do I know if the fast changes detection was used?
One journal is maintained for each NTFS volume and stored in the NTFS metafile named $Extend\$UsnJrnl. It begins as an empty file. Whenever a change is made to the volume, a record is added to the file. Each record is identified by a 64-bit Update Sequence Number or USN. Each record in the Change Journal contains the USN, the name of the file, and information about what the change was.
The Change Journal describes the changes that took place using bit flags, therefore it does not include all the data or details associated with the change. For this reason the Change Journal cannot be used to undo operations on files within NTFS.
How to activate/deactivate the “Smart file scanning mode” option?
Since version 5.4 of Backup4all, this option is activated for all new jobs. It can be activated manually for jobs created with an older version of Backup4all. To do that, open Backup Properties -> Advanced page. Select the “Smart file scanning mode” option, then press Save.
If for some reasons you don’t want that option to be used, simply uncheck it from the above mentioned location.
If you want to disable the "Smart file scanning mode" option for all jobs, or you want to customize the way it works, please go to File->Options->Backup. There you can set the option to never be used, to always be used or depending by the number of source files.
When the “Smart file scanning mode” applies?
The “Smart file scanning mode” option is used in all cases with the following exceptions:
- User is not an administrator and the sources are on local drives. For standard users this option works only for external drives.
- The source drive is not NTFS formatted.
- Sources are not on local drives (ex: network drives). This option also works for local removable NTFS drives (stick, external hard drive, removable drives)
- Backup job has relative file date filters are (ex: "older than x days").
- If the file/folder filter has changes since the previous backup.
- The journal will not be used at first backup (all sources are newly added).
- The journal will not be used for full backup executions.
- The journal will not be used when a source is newly added to backup
- The journal will not be used when the source is changed by including other subfolders/files that were previously excluded
- Because parsing the NTFS journal can be slower in some cases than parsing the files, the option will not be used if there are less than 20,000 files & folders in the backup. The 20,000 count is calculated as sum of all files and all folders already present in backup catalog, before the current backup execution.
How do I know if the fast changes detection was used?
In order to find any information about “Smart file scanning mode” in the backup log, just search for “USN journal” in log.
Here are some examples of USN Journal loggings:
- *Using USN journal for the following sources: F:\*
- *Cannot use USN journal for this backup. Reason: This is the first backup run.*
- *Cannot use USN journal for this backup. Reason: Filters have changed*