Exchange deduplication ratio

Hi,

 

I did Exchage full backup to new deduplication store with DP 9.0. The ratio is 1.8 : 1, I was expecting more. What is your dedup ratio for Exchange? We have 800 GB database with ~150 users and 5 years mails and share folders in it.

 

Thank you, Jan

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  • I usually see much better dedupe results. Have you considered that you have many pre-compressed data (pictures, archives, encrypted files) inside your Exchange databases?

     

    Regards,

    Sebastian

  • Thanks, I don't think that compression has anything to do with deduplication. I was just expecting that large attachments that are shared between several mailboxes will be deduped. Maybe there are not so many of them, but usually you send those inside company, so sender and at least one recipient. What are ratios you achieve?

     

    I did not found any settings that affects deduplication.

     

    Kind regards, Jan

  • Don't unterestimate the negative impact of compression on deduplication. Usually you will see better dedupe results if you store more copies (of the same backup) on the dedupe target. If you look at the job, you should look at the per object and overall dedupe ratio. Personally I think the overall dedupe ratio is not calculated correctly. Here is a per object result where I keep 14 copies on disk.

     

    [Normal] From: BSM@CM.domain.com "MSX_BACKUP" Time: 08.09.2014 20:20:22

    Target-side Deduplication Statistics for MSX.domain.com:/Microsoft Exchange Writer(Exchange Information Store)/Microsoft Information Store/0a4df680-5d47-4801-ae4f-4b7398d24f58/File "MSVSSW-APP".
    Using device: "B2D_CM [GW 1584:1:6136511032400778809]@CM.domain.com":
    Mbytes Total: ................. 74042 MB
    Mbytes Written to Disk: ....... 169 MB
    Deduplication Ratio: .......... 438.1 : 1

     

    While the Overall Deduplication Ratio is 4.8 : 1 for the job. This must be due to some very small VSS objects that have a dedupe ratio of 1:1. You can share a full session report and details on how many full/incr you keep on your store.

     

    Regards,

    Sebastian

  • I see...I was talking about dedup ratio after one single full backup to empty store. Of course subsequent full backups should achieve high ratio per object provided the object data doesn' change a lot.

     

    Kind regards, Jan