Forum Discussion

nbuno's avatar
Level 6
14 years ago

Dedup query.

Hi Guys,


NBU 7.1

PureDisk Media server side De-dup.


As far as i have understood dedup it creates the fingerprints by keeping "some data" in reference on MSDP.


My question is : is that data is nothing but the last full backup ? 

& if not then what happens to that data after all ? are we always gonna see some data residing on DISK pool as it may be that referenced data that was used for fingerprinting someday?



help me pls ..



2 Replies

  • Hello nbuno,

    MSDP can be enabled on multiple media server out of which only 1 server acts as Storage Server for Deduplication where Deduplicatoin database resides.

    Deduplication database contains metadata of all deduplication information in environment backed up through various MSDP servers.

    Metadata includes information about unique fingerprint that identifies the file content, on which client the file resides,where it resides on the client,files owner, creation date, etc.

    Netbackup database maintains the actual Image format of the backup which holds the info of retention period. On the retention period is reached netbackup tells to the Deduplication database to expire the segments on the disk pools linked  to that image. Dedupliation manager looks for the sengments to expire and if the segments are not associated to any other files then it will be expired and if the segment is linked to some other files then file will still remain on disk till all the linked files are expired.

    **Dedupliation Database is not included in Netbackup Catalog.


    Is this the information you are looking for?




  • very much so i was looking for this but as a matter of fact i was trying to get an explanation more realistically.

    Here are the 2 scenarios :

    1.Lets say we backed up an Excel file A for the first time in Monday's FULL backup ,now on monday night it got changed so the in Tuesdays INC backup we backep up what ? entire file (as generally NBU do normally) or it will refer the mondays file and create pointers (means dedup it) ?


    2. Whatever it will do,if mondays full backup has retention of 1 week then what will be the backup on next Monday ? another completed full or it will again take pointers from the last backup ?



    Such are the questions confusing me..any thought ?