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DLO with Dedupe Enable : Local Disk Space


I just have a question.
I use Symantec Backup Exec and DLO since a very long time, and up ton now I used and old DLO version (BE 2010 R3) without any problem.

Following some company buy out, I am now testing DLO 7.5 in our Global Company.

So I have installed SQL Server, DLO 7.5 etc.. and tried a backup with Dedupe enabled. I have seen that for Dedupe, DUDF is enabled and used but I quickly stop the backup because of the place taken on my drive. When I stopped, I had 22 Go of Backup (21 Go on Dedupe Storage and 1 Go on Data Storage) but i also had 20 Go on my local appdata on my laptop. A lot of my user don't have a lot of place on their laptop.

So, Is it normal to have a very big local disk space when using dedupe ?
Is there a solution to use dedupe without taking too much place on local drive ?

I know that with this solution we are able to backup and restore offline but it's not what I want.

And does it mean that I shouldn't use Dedupe ?

Thanks in advance,


7 Replies

This KB may help -

This KB may help -

Thanks, I already read it


I already read it yesterday.
But I didn't really understand the solution. Because i really had 20Go of data on my computer and if I put a limit to DUDF the backup stop working. And my frees space disk on my local disk decrease during backup.

Could you explain it to me ?


Thanks, I already read this


I already read this yesterday.

But I am not sure I have all understand. Because in my case, the backup took 20 Go on my local disk and i could see the free space on my disk decrease.

Then, if I put a limit on DUDF, the backup stopped working after reaching the limit.

Could you explain me the functionnality of Dedupe and the relation with DUDF.

Are you sure DUDF take no place on disk ?



When a DUDF is enabled, all

When a DUDF is enabled, all backups first go to the DUDF and once, the client system can access the NUDF, the data is transferred from the DUDF to the NUDF. Think of the the DUDF as a temporary staging area in this case.

And the data usually remains on the DUDF is the network copy hasn't started yet and/or if the DUDF is configured to keep a certain amount of revisions.

Lastly, from a Dedupe perspective, the files are deduped once they are completely new and unprotected. Post this, the backup type switches from a "DeDupe mode" to "Delta mode" whereupon delta file transfer comes into the picture. And delta computation always happens on the DUDF.


Hi, I thought that with


I thought that with Dedupe, DUDF is mandatory and even if we put 0 revision for DUDF, data remains on DUDF. No ?

I have modified the configuration of my profile to test other options

I have launched a new backup and I will give you an update tomorrow. Up to now, I have 3,65 Go protected on network for 1 Go of data on my local disk in appdata/local/symantec/dlo


That's right. DUDF is

That's right. DUDF is required for DeDupe as the post the initial backup of a file, "delta mode" transfer comes into play.

Hi,   Just an update. So, I



Just an update.

So, I have launch a new backup with dedupe and a limit of 4% for DUDF.

I have 9 Go used on my local drive, and the stats on the dedupe storage are :

Total size : 25,945 GB

Size on disk : 4,007 GB

Deduplication Savings : 84.555% (21,938 GB)

So, even if I put a limit on DUDF, backup is OK. It still backup on network, but for a better use of dedupe we need place on local disk. So not easy to use in my case...

I'm going to try a backup without dedupe and only on network to test the performance.

I will give you a feedback.