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Full and incremental backups are the same size.

Created: 17 Oct 2012 | 7 comments

I´ve got a strange behavior when backing up CIFS-shares on a EMC Vnx3100 with Backupexec 2012.
The job is set do a full backup saturdays and incremental backups every other day, and the job is configured to use "modified time" and all AOFO-options are unchecked.

The problem is that the full backup runs without any errors and att good speed (roundabout 3500MB/min) and finishes with an exception notification that no agent was found on the remote server. This notification is normal behavoir as I understand it.
The problem is that the incremental backups is the same size as the full backup (about 850GB) instead of about 5-10GB which would be the normal size of new and changed files.

Do anyone have a solution to this?


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sazz.'s picture

Have you checked if it is resetting the archive bit.Are you trying with archive bit? Try using modified time.

Check this also where Colin has explained in very good way

TechMark's picture

As I wrote above, the job IS configured to use "modified time", since the EMC VNx 3100 NAS is a UNIX (Linux) based system and don´t make use of the archivebit on it´s filesystem.

The problem is that BackupExec doesn´t seem to use the modified time or something is changing the modified time for the entire volume every day.

Jaydeep S's picture

Edit -

All backup methods (Full, Differential, Incremental using Modified Time, etc.) are supported only if the Agent for Windows Systems (AWS) or Remote Agent for Linux/Unix Systems (RALUS) is installed.  For systems unable to have either agent installed, only the backup method FULL is supported.

 Systems without an agent are unable to gather the information necessary to support any other backup method

Refer to 

TechMark's picture

Ok, I understand that this is the reason but I fail to see why BackupExec works that way.

If you read the BackupExec2012 Adminguide it states the following.

Method: By modified time

 Backup Exec uses the Windows Change Journal to determine
if a file has changed since the last time it was backed up. If
the Change Journal is not available, modified time is used.
When Backup Exec runs a full backup or incremental
backup, the time the backup launches is recorded in the
Backup Exec Database. The next time you run an
incremental or a differential backup, Backup Exec compares
the file system time to the backup time from the Backup
Exec Database. If the file system time is later than the
database time, the file is backed up. If the file's modified
time is older than the previous backup's modified time, that
file is not backed up.

Note: A file's last modified date and timestamp does not
change when the file is copied or moved. To ensure that the
files are protected, run a full backup after you copy or you
move files. If you have the Advanced Disk-based Backup
Option, you can run synthetic backups to ensure that any
copied or moved files are protected.
When you run an incremental backup, Backup Exec records
a new time in the Backup Exec Database. The database time
is not updated with differential backups.
Using modified time allows Backup Exec to run differential
backups on the file systems that do not have an archive bit,
such as UNIX.
Backup Exec adds the time of the backup to the Backup Exec
Database only if the full backup job completes successfully.
If it does not complete successfully, subsequent differential
or incremental backup jobs back up all of the data instead
of only the data that changed

As I understand it BackupExec will try using Windows change journal and if that isn´t available it uses the files/folders "last modified" time.
When you backup CIFS-shares on a NAS that don´t have the RAWS- or RALUS-agent BackupExec uses the mediaservers agent to perform the backup.
Why can´t it use the files "last modifed" time then?
As far as I know and can see in our shares the filesystems on the EMC VNXe3100 presents the last modified time.

Jaydeep S's picture

Marcus, due to the lack of remote agent (RAWS / RALUS) Backup Exec is not able to gather the required information for Incremental/Differential backups.

My only suggestion at this time would be to ask you to add a topic in ideas and suggestions.

sazz.'s picture

Hey Marcus,

I think you forgot to read the link I provided.

Eugenio's picture

How to do a full backup every 5 minutes, with policy oracle, with netbackup 7.5