SYMTOMS
The incremental backup size increases every time when you backup files from a snaphot like “Snapview snapshot or a VCB snapshot”.
CAUSE
When performing incremental backups Networker can use different methods see which files have changed since the previous backup.
Networker can use the “archive bit” or “timestamps”, the problem is Networker use the “archive bit” based from the “Windows change Journal” to do its incremental backup.
Why it’s a problem?
Networker says what to backup in compare the value of “archive bit”, “last written time” and “last creation time” from the last full backup.
During the backup Networker reset archive bit, but it reset the archive bit on the snapshot and not to the original drives.
Sample :
When you do a “incremental” backup after a full backup.
During the backup, Neworker read “archive bit” value and ...
- If “archive bit” value is “on”, the file is backed up and set to “off”.
- If last written time “or” last creation time “>=” last full backup, the file is backed up and set to “off”.
- If last written time “and” last creation time “<” last full backup, the file is backed up and set to “off”.
RESOLUTION
You must force Networker to use “timestamps” and not “archive bit” to backup files.
To do that open the “Networker Change Journal” and disable it for all volumes in the source server of snaphot and the backup server or storage node.
You can also add an system environment variable “NSR_AVOID_ARCHIVE=yes” on Networker Server / Clients do you want to force to use “timestamps”
Sample :
The snaphot of a “serverA” is mounted on a backup server named “serverB”, you must disable the “Networker Change Journal” on both servers “SERVERB and SERVERA” or/and add a system environment variable “NSR_AVOID_ARCHIVE=yes”.
Remark :
The “Networker Change Journal” can be only disable on devices that are online when you run it, if you want disable a device that is not online you must use this command at command prompt:
- C:\> fsutil usn deletejournal /D [Drive Letter]: