Forum Discussion

Pierre_J's avatar
Pierre_J
Level 4
6 years ago

How to determine daily change rate

Hello All, It seems odd but I have difficulties determining the daily change rate of the data I am backing up. We write to a dedup device (Data Domain) so from that side it is hard to get some figu...
8.1.2
windows server 2012
  • davidmoline's avatar
    davidmoline
    6 years ago

    PIerre

    Read the section in the VMware admin guide chapter 9 - "About Reporting the amount of Accelerator backup data that was transferred over the network".
    There are three commands you can use bpdbjobs, bpimagelist and bpclimagelist.

    With any of these you can cobble together a script to create the output you need.

    Cheers
    David

  • davidmoline's avatar
    davidmoline
    6 years ago

    Hi Pierre

    The numbers reported are the accelerated numbers - so will be showing the change blocks from the VM itself. This is the data transferred from the VM backup host to the media server (which may be the same machine). 

    There may be additional information in the job details that indicate the amount of deduplicated data sent to the Data Domain (although I'm not 100% sure this is reported for DD, like it is for an MSDP storage unit).

    So for eaxmple you have a 100GB VM. For an accelerated backup (with say 10% change rate), 10GB would be rquired to be read by the media server. Of this 10GB, DDBoost may not require some of this as the data already exists in the DD (this is the deduplication performance). 

    The bpimagelist command (and others mentioned) will show the 10GB value of the acceleratoed backup, NOT the amount of data sent to the DD.

    Cheers

Pierre_J's avatar
Pierre_J
Level 4

Hi David,

Thanks a lot for this hint.
Is this the way to discover the clean change rate of a VM or are these numbers 'polluted' with DDboost optimizations?
I mean the optimization for instance of 2 identical VM's where DDboost says 'this data is already on the Data Domain, it is not neccesary to send it again'.

davidmoline's avatar
davidmoline
Level 6
6 years ago

Hi Pierre

The numbers reported are the accelerated numbers - so will be showing the change blocks from the VM itself. This is the data transferred from the VM backup host to the media server (which may be the same machine). 

There may be additional information in the job details that indicate the amount of deduplicated data sent to the Data Domain (although I'm not 100% sure this is reported for DD, like it is for an MSDP storage unit).

So for eaxmple you have a 100GB VM. For an accelerated backup (with say 10% change rate), 10GB would be rquired to be read by the media server. Of this 10GB, DDBoost may not require some of this as the data already exists in the DD (this is the deduplication performance). 

The bpimagelist command (and others mentioned) will show the 10GB value of the acceleratoed backup, NOT the amount of data sent to the DD.

Cheers

  • Pierre_J's avatar
    Pierre_J
    Level 4
    6 years ago

    Thank you David!

    • Genericus's avatar
      Genericus
      Moderator
      6 years ago

      You should get a daily report from your data domain as well: autosupport.

      It has a section like this:

      From: 2019-06-21 06:00 To: 2019-06-28 06:00

                           

                          Pre-Comp   Post-Comp   Global-Comp   Local-Comp      Total-Comp

                             (GiB)       (GiB)        Factor       Factor          Factor

                                                                            (Reduction %)

      ----------------   ---------   ---------   -----------   ----------   -------------

      Currently Used:*   3339978.5    409263.6             -            -     8.2x (87.7)

      Written:                                                                          

        Last 7 days       830894.9     68783.8          7.5x         1.6x    12.1x (91.7)

        Last 24 hrs       132958.5      9199.8         10.3x         1.4x    14.5x (93.1)

      ----------------   ---------   ---------   -----------   ----------   -------------

       

      Last 24 hours I wrote 133TB to the data domain, the post comp was 9TB - that is the change rate.