partition extended mode

Last post 08-11-2017, 9:11 AM by Ali. 8 replies.
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  • partition extended mode
    Posted: 08-07-2017, 11:35 AM



    i was going through documentation and read about partition extended mode. 

    I have a query on how we configure this in commvault environment. 

    we are using primary global partition(2 partitons)  dedup. 

    how do we configure secondary copies so that we can acheive partition extended mode config. 

    We wanted to configure secondary dash copies. 

    do i have to create a another global dedup policy with 2 partitions and assosciate my secondary copies to that global dedup. can i acheive the purpose of partiton extended mode by doing this. 


    also is there a way i can choose or set multiple datapaths for my secondary copy in a storage policy. 

  • Re: partition extended mode
    Posted: 08-09-2017, 4:18 AM

    seems questions about partitioned or extended mode of ddb are quite detailed to answer, and rarely get the right answer to heart of questioner.


    I tried to help answer as much as I know :

    for extended partiion mode, yes, you need to create one more library, create global ddb on top of it.

    Then just create a selective copy in existing storage policies, and point these copies to global ddb on this newly created ddb.

    moving only selective monthly or yearly backup jobs onto this newly created ddb with auxcoopy job.

    Again, about the benefit of this scheme :

    configuring extended mode ddb can reduce the size and number of entries in primary ddb, which you should use for backup/restore frequetly, and leave the occasionally ones in other ddb. this will help guarantee the speed of primary ddb from day one to years later. (if not, your primary ddb will be clumsy day after day, and your SLA of backup/restore/auxcopy may be slower when time pass by.


    Please help correct me if I am wrong, team.

  • Re: partition extended mode
    Posted: 08-09-2017, 4:18 AM

    also if what I said is correct, what you can see about using extended mode is, you need to have more backup disk space to keep new baseline in second ddb, comparing to keep them all in one primary ddb. 

    If you are purchasing a hardware with X00+ TB of backup disk, you need discount of storage purchasing to help reduce the cost. but in smaller deal, that will cost you some.

  • Re: partition extended mode
    Posted: 08-09-2017, 3:33 PM

    Hi JourneyMan,


    Thank you for the response.

    I have an extended Question on this:)

    When i use a partiotioned dedup with 2 paritions does my DDB db between both paritions be in sync ? - Will both the DDB db always have same data

    If yes Which log can show my how and when sync happens between  thm

  • Re: partition extended mode
    Posted: 08-10-2017, 10:57 AM
    • Ali is not online. Last active: 03-05-2018, 11:33 PM Ali
    • Top 10 Contributor
    • Joined on 08-05-2010

    For partion DDBs the partitions do not sync, each partition keeps a unique set of records.

    In some cases if/when a partition may go offline, the DDBs may share common records.

    A 'sync' happens when a DASH copy runs, and that means there's a calculation on which unique and duplicate blocks exist and need to be sent over the wire for being written to the storage target.

  • Re: partition extended mode
    Posted: 08-10-2017, 10:16 PM

    Ali, thanks a lot for clarifing the syncing method of parititoned ddbs. 

    I am also in doubt about ddbs in partitioned mode wheter it syncs or not sync.


    anyway, I am curiuos about partitioned ddbs in my enrironemnt, which need to ask you so please help explain.


    from day 1 I started configuration partitioned ddbs in 2 node grid, when I ran the first backup job into this grid, I saw both ddb patitions in both nodes has the same data in ddb direcotries. afte I ran backup job 2, also, the both parititions still write the same ddb content in ddb direcotry (which look like it is syncing each other)

    Could you please explain this situation? when data is written in grid with partitioned ddbs, does the ddb records will be distributed into every online partition, and leave the offline ones out of syncing?

    During posting this question, I also test again by running a backup job into grid, which is written into MA1. When backup job finished, I look at the ddb directory of both MA1 and MA2, and found that MA2 also have bytes increased in ddb directory, with the same file name and bytes in both MAs. (looks like it also write ddb entries in MA2 as well, even MA2 is not selected to be the target of backup)

    This is the question that I asks previously in forum but no reply at all. 

  • Re: partition extended mode
    Posted: 08-11-2017, 1:02 AM
    • Ali is not online. Last active: 03-05-2018, 11:33 PM Ali
    • Top 10 Contributor
    • Joined on 08-05-2010

    It depends on the blocks coming into the DDB, if its unique or not, the DDB will decide which block to write to which partition based on a function it calculates on each block.

    Lets say there is block A which writes to partition 1 and block B which writes to partition 2.  If partition 2 goes offline, block B will write to partition 1, once partition 2 comes back online and the DDB see's block B coming in, it will write it going forward to partition 2, again syncing, its first come first serve and then it will clean up those blocks based on when jobs been retention no 'synch-cleanup'.

    Does that make it clear?

  • Re: partition extended mode
    Posted: 08-11-2017, 6:13 AM

    Hi Ali,

    I am still not clear about how ddbs get updated in this case.

    Anyway, I change the question as below may make it clearer.

    If I have 1 MA with newly created 1 DDB without other parittion, and I backup jobs into this MA, how about the ddb size, comparing to backing up the same jobs into grid with 2 MAs with 2 ddb partitions? (in case that both MA in grid are always online during backup)

    Question : Is ddb size in standalone MA equal to total combined ddb size of both partitions of MAs in grid?


  • Re: partition extended mode
    Posted: 08-11-2017, 9:11 AM
    • Ali is not online. Last active: 03-05-2018, 11:33 PM Ali
    • Top 10 Contributor
    • Joined on 08-05-2010

    Correct, it should be about the same since there is only 1 partition for the blocks to be written to.

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