Showing results for 
Search instead for 
Did you mean: 

best way to free space in a deduplicated storage

Level 2


we have to 31TB deduplicated storage in our netbackup 5250 appliance .  we have 1.37 TB remaining and we want to have more space. We tried to expire some backups from catalog, those images were deleted but the free space  is always around 1.20. i guess deduplication is the reason why. we have 2.5 deduplication rate.  here are some info gathered that can help


 Data storage Raw Size Used Avail Use% 32.0T 30.7T 29.4T 1.3T 96% Number of containers : 121997 Average container size : 265072582 bytes (252.79MB) Space allocated for containers : 32338059799681 bytes (29.41TB) Reserved space : 1408448624640 bytes (1.28TB) Reserved space percentage : 4.0%


 Storage Pool Raw Size=32.0TB Storage Pool Reserved Space=1.3TB Storage Pool Size=30.7TB Storage Pool Used Space=29.4TB Storage Pool Available Space=1.3TB Catalog Logical Size=74.1TB Catalog files Count=15270 Space Allocated For Containers=29.4TB Deduplication Ratio=2.5 

Question: What is the most efficient way to free space because expiring many backups seem not to be efficient

thanks in advance


Partner    VIP   

The curse of deduplication ...

My hints:

  • Look for clients with high amount incremental backup, typical is'a error. Database not excluded etc.
  • Looks for client with bad dedupe and move them somewhere else. Scripting required.
  • Stage the oldest backup to tape, they are likely also the backup images that holds most unique fingerprints. 

Do not:

  • Remove smaller backup images - they don't hold enough unique fingerprint to make a impact.

Make a plan for extending disk space, in most installations space consumption increases with 20% or more per year. 


Level 2

thanks @Nicolai 
I didn't understand you first hint.  what to i need to do for databases?

Partner    VIP   

hi @ndiayepjn 

Databases needs to excluded from file system backups, but is often forgotten. Looks for file system backup where the incremental and full backup is almost the same size. That is usually a good indication something is wrong. 

A operation like that will reduce the space load on your MSDP.


Good Luck!

I took my deduplicated retention from 4 weeks to 2 weeks, a 50% reduction - and gained 10% space.

It is the biggest issue with space - you won't know what you will get until you do it.


NetBackup on Solaris 11, writing to Data Domain 9800
duplicating via SLP to LTO5 & LTO8 in SL8500 via ACSLS