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Why run differentials?

Created: 17 Mar 2013 • Updated: 21 Mar 2013 | 6 comments
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So pretty basic question here, why run differential back ups.  Maybe this is the point of them, but the seem a little redundent.  I know that they basically backup all changes since the last full backup, so more or less if you ran multiple differential backups in one week you would be writing some of the data twice.  It seems like incrementials through out the week and a full backup at the end of the week would be the way to go...  How would differential backups fit into the equation, what point would they serve?

Also one other question, we have an Access database that is prone to coruption so we have been running a full backup on the database multiple times a day.  I know that this a really silly question, but I always like asking because I like to get someone elses opinion.  There is no reason why we could not just run incrementials on this database and achieve the same restorability.  

 

-Thanks as always

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pkh's picture

You run differentials to ease the recovery.  With differentials, you only need to restore the last full backup and the last differential backup, whereas with incrementals, you need to restore the last full backup and ALL the incrementals since that full backup.

You can backup your Access database using incrementals, but the result is the same as running a full backup, the whole database would be backed up.

Sym-cr@zy's picture

Hi PRS,

As you already mentioned that you are aware of the method of Incremental and Differential Backup. I won't discuss much on that, you can refer the link below:

What are the differences between Differential and Incremental backups?

http://www.symantec.com/docs/TECH7665

I would rather state few strategic differences:

Incremental Backups:

Advantages:

  • Less bandwidth consumption between the Media Server and the Semote server during the data transfer
  • Less amount of space occupied on the media

Disadvantages:

  • To bring back a crashed server, up and running you would require a full backup and all the consecutive incremental backups
  • Restore of the complete server takes longer time as it has to find and restore full + all the incremental backups.

Differential Backups:

Advantages:

  • More bandwidth consumption between the Media Server and the Semote server during the data transfer
  • More amount of space occupied on the media

Disadvantages:

  • To bring back a crashed server, up and running you would require a full backup and only the last differential backup (as it contains all the changes since the last full backups)
  • Restore of the complete server takes lesser time as it has to find and restore full + only last differential backups.

 

 

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Colin Weaver's picture

I think you got the differential advantages and disadvantages the wrong way around.

Sym-cr@zy's picture

 

Yup Colin..My Bad. Thanks for notifying me... smiley

 

Differential Backups:

Disadvantages:

  • More bandwidth consumption between the Media Server and the Remote server during the data transfer
  • More amount of space occupied on the media

Advantages:

  • To bring back a crashed server, up and running you would require a full backup and only the last differential backup (as it contains all the changes since the last full backups)
  • Restore of the complete server takes lesser time as it has to find and restore full + only last differential backups.
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CraigV's picture

...that's what happens when you copy the wrong information into the wrong place!

Alternative ways to access Backup Exec Technical Support:

https://www-secure.symantec.com/connect/blogs/alte...

Donald Eady's picture

I think that the biggest difference is going to be in the amount of space being occupied by the backups. You will see more space being occupied by the differential as it will be backing up all data that has changed since the full "I belive you mentioned this earlier" as far as the restore effort it would be about the same. With 2012 you need not restore the full then run a restore of the following inc's/diff's youre able to just select the more recent backup job be it full incremental or differential and restoere. Backup exec will grab all neccessary media needed and restore "Provided it has access to the media if it doesnt it will call for it". 

I hope this posting was helpful