Good Morning, 

My understanding is that the netapp on  disk is keeping track of changed 
blocks, but that backup software that is written the backup to tape understands 
files.  So the backup software is reading  the whole file including both the 
unchanged blocks and the changed blocks and writing them to tape.

The netapp is using the old unix dump command  to read the files and write them 
to tape. Netbackup adds its header files to the backup stream. Other then    
software such as snap mirror or snap vault I do not believe that the netapp 
have an api for only passing the changed blocks to the backup software.  
One could wonder if this will change with the new world of dedupe. 

-----Original Message-----
From: veritas-bu-bounces AT mailman.eng.auburn DOT edu 
[mailto:veritas-bu-bounces AT mailman.eng.auburn DOT edu] On Behalf Of n_ashwin
Sent: Tuesday, July 27, 2010 7:46 AM
To: VERITAS-BU AT MAILMAN.ENG.AUBURN DOT EDU
Subject: [Veritas-bu] NDMP backups from Netapp using Netbackup


One of my customers says that his NDMP incrementals are 3TB in size, while his 
full backup size is 6TB. However, when he checks for the block changes in 
Netapp console,it reports block changes amounting to 60GB

I was of the impression that NDMP incrementals happen at the block level, in 
which case his incremental size had to be around 60GB.

Can someone explain to me why this is so.

Appreciate if you could get down to nuts and bolts and tell me how NDMP treats 
incrementals/level backups.

dp_nash

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