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Backup Exec and HP Tape Drives: Full & Differential Backups - Tape Dependancies

Created: 07 Aug 2013 • Updated: 07 Aug 2013 | 8 comments
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I am trying to understand the dependancies between the Tapes when it comes to Full and Differential backups in BE 2010.

I am using an 8 slot HP Tape Drive to backup my data to from a NAS Device.

I have a succesfull FULL Backup onto the Media in slot 05.

I wish to take the differrential backup of the target and back it up to the Media in Slot 06.

My queries are as follows:

  1. I have created 2 backup jobs, One for full and One for diferrential backups from the same target.
  2. The differential backup as i understand does 'not' reset the archive bit which is initially set by the full backup.
  3. Having said that, where exactly is this 'archive bit information' stored ? Is it on the Tape containing the full backup or somewhere in an internal database within BE ?
  4. The reason i ask the question is because i am trying to understand wether the Tape in Slot 05 containing the full backup is required to be present while BE performs the diferential backup in Slot 06 ?
  5. If the above (point 4) is true, and if I have already removed the tape from Slot 05 post a Full Backup, can I just put the tape back in to Slot 5 (or any other available slot apart from Slot 06), run an inventory within BE and continue with the Differrential backup normally ?

Thanks a lot !

Operating Systems:

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Donald Eady's picture

The archive bit is a windows file attribute.. Backup Exec looks at this to determine whether or not the file has changed and needs to be backed up. 

Additionally your differential backup should run even if the tape containing the full is not present please see document below


forgot to attach document see below


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Donald Eady's picture

Please also note that your full and differential backup jobs need to be connected by / a part of the same policy 

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pkh's picture

This is only a requirement for Exchange backups.  It is not a requirement for file backups.

Mac1983's picture

Oh thanks pkh

i failed to mention that the backups were for a Domain Controller, An Application Server and a NAS Device !

thanks a lot !

sidd3009's picture

Hello Mac,

Please refer to the image I picked up from the forum(I've modified it in terms of Backup Exec):


Based on the above image,

An Incremental backup backs up only the selected files that have their archive bit set to ON, setting them back to OFF. This results in a backup of all files that are new or changed since the last backup, whether it was a full or an incremental. The advantage of an Incremental is that it takes the least amount of time and media of all the backup methods.

Differential backup backs up only the selected files that have their archive bit set to ON but does not set the archive bit back to OFF. A Differential backup will back up all selected files that are new and changed since the last full backup. The advantage of a Differential comes at restore time; you'll need only the last full backup and the last differential to get a complete restore. In the case of restoring with Incremental backups, all the Incremental backups since the last full backup plus the last full backup would be necessary.

In simple words,

Differential Backup:
This will backup all changes since the last Full backup.

Incremental Backup:
This will backup all changes since last backup - Full or Incremental.

Since you are using Backup Exec 2010, you may remove the tape present in Slot 5(which has a Full backup) and insert a different tape in the same slot to run a Differential backup to it. 


Siddhant Saini
Former Symantec Senior Technical Support Engineer 
Symantec Technical Specialist 
Symantec Certified Specialist.

Mac1983's picture

Hi Donald

I have created separate jobs for Full and Differrential Backups.

Can i create a policy to link the two ?

thanks !

Donald Eady's picture

Should be able too... may be easier to just create a policy then create new jobs using the policy... have a look at page 521 of the 2010 admin guide... it details the creation of a policy and the relationship of jobs that share that policy...

if you dont have a copy of the admin guide you can download it here

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