Use Change Journal in Incrementals

NetBackup offers support for the Microsoft change journal in order to enhance performance of incremental backups on Windows 2000, Windows XP, and Windows Server 2003 systems. By enabling the Use Change Journal in Incrementals check box, NetBackup can provide faster incremental backups for NTFS 5 (and later) volumes storing large numbers---possibly millions---of files. Use Change Journal in Incrementals is available only when a valid tracker database exists on the applicable volumes. Default: Not enabled.

Enabling Use Change Journal automatically enables Incrementals are based on timestamp.

The Microsoft change journal is a disk file that records and retains the most recent changes to an NTFS volume. By monitoring the change journal, NetBackup can determine which file system objects have changed and when. This information is used to shorten the discovery process performed by NetBackup during an incremental backup by making a file system scan unnecessary.

This property appears for Windows clients only.

Determining if enabling change journal support is useful in your NetBackup environment:

Utilizing NetBackup support for the change journal is beneficial only where the volumes are large and relatively static.

Suitable candidates for enabling NetBackup change journal support:

• If the NTFS volume contains more than 1,000,000 files and folders and
  the number of changed objects between incremental backups is few (less than 100,000), the volume is a good candidate for enabling NetBackup change journal support.

Unsuitable candidates for enabling NetBackup change journal support:

• Support for the change journal is intended to reduce scan times for incremental backups by using information gathered from the change journal on a volume. Therefore, enabling NetBackup change journal support is not recommended if the file system on the volume contains relatively few files and folders (hundreds of thousands). The normal file system scan is suitable under such conditions.
• If the total number of changes on a volume exceeds from 10 to 20% of the total objects, the volume is not a good candidate for enabling NetBackup change journal support.
• Be aware that virus scanning software can interfere with the use of the change journal. Some real-time virus scanners intercept a file open for read, scan for viruses, then reset the access time. This results in the creation of a change journal entry for every scanned file.

This property appears for Windows clients only.

Guidelines for enabling NetBackup change journal support

• A NetBackup client utilizing change journal support must belong to only one policy. This avoids the confusion caused by multiple backups setting conflicting update sequence number (USN) information in the permanent record.
• After selecting Use Change Journal in Incrementals, the NetBackup client daemon service must be restarted on the target system. A full backup of the target system must be completed under change journal monitoring to enable change journal-based incrementals.
• Change journal support is not offered for user-directed backups. The USN stamps for full and incremental backups in the permanent record will not be changed.
• NetBackup support for change journal works with Checkpoint Restart for restores.
• Support for change journal is not offered with several NetBackup options or VERITAS products. Enabling the Use Change Journal in Incrementals check box in the Windows Client host properties will have no affect while using the following options or products:
• True Image Restore (TIR)
• True Image Restore with Move Detection
• Synthetic backups
• Intelligent Disaster Recovery (IDR) (See the NetBackup System Administrator's Guide, Volume II.)
• Bare Metal Restore (BMR)