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ssholl's avatar
ssholl
Level 2
11 years ago

Deduplication Ratio 0.0%

Hello,

 

we have client side deduplication enabled and on the surface all looks well, we ran it for the first time this weekend and it completed.

 

however looking at the job log it says the deduplication ratio is 0.0:1. However looking at the same job history it shows the below which makes me think it is deduplicating?

will it deduplicate data from the same job or will it only do it from previously run jobs?

 

any help would be great.

 

Byte count          : 4,485,426,452,022 bytes
Job rate            : 1,769.78 MB/Min (Byte count of all backup sets divided by Elapsed time for all backup sets)

Scanned byte count  : 88,356,091,904 bytes
Stored byte count   : 3,231,561,389,056 bytes
Deduplication ratio : 0.0:1
2010
Backup and Recovery
Backup Exec
Deduplication Option
Windows Server (2003-2008)
  • pkh's avatar
    pkh
    11 years ago

    In very simplistic terms, the dedup process chops up a file and compare the chunks to what is stored in the dedup device.  If the chunk is found, it would not be stored.  The chunk that is in the dedup device can be from anything, even the file that is currently being backed up.

    Copying a file and making small changes to a file does not mean that the copies will be dedup'ed.  For example, you have a file with this content

    1234567890qwertyuiop

    and this is stored in the dedup device as chunks like this

    12345 67890 qwert yuiop

    Another user edit copy this file and insert a A

    A1234567890qwertyuiop

    This file will be stored as

    A1234 56789 0qwer tyuio p

    You can see that the data chunks from the two files are different.  Hence, there is no dedup.

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  • CraigV's avatar
    CraigV
    Moderator
    11 years ago

    ...you haven't tagged the correct version of BE. You've tagged BE 10 and earlier. Which version of BE that uses dedupe are you using? 2010, 2012, 2014?

    Thanks!

  • pkh's avatar
    pkh
    Moderator
    11 years ago

    we ran it for the first time

    Your result is expected.  You would not get a good dedup ratio immediately because there is no data stored in the dedup folder.  You need to run it over a period of time to built up your existing data to achieve dedup savings and increase the dedup ratio.  The idea behind dedup is that if the chunk of data is already in the dedup folder, it would not be stored again.

  • ssholl's avatar
    ssholl
    Level 2
    11 years ago

    Hi Pkh, thanks for the comment, i was expecting it to find duplicates during the backup job itself on the same server, its a file share so i would of expected so see people copying a file and making small changes?

     

    will it only dedupe from a previous backup attempt?

     

    (ive tagged the right version now)

  • pkh's avatar
    pkh
    Moderator
    11 years ago

    In very simplistic terms, the dedup process chops up a file and compare the chunks to what is stored in the dedup device.  If the chunk is found, it would not be stored.  The chunk that is in the dedup device can be from anything, even the file that is currently being backed up.

    Copying a file and making small changes to a file does not mean that the copies will be dedup'ed.  For example, you have a file with this content

    1234567890qwertyuiop

    and this is stored in the dedup device as chunks like this

    12345 67890 qwert yuiop

    Another user edit copy this file and insert a A

    A1234567890qwertyuiop

    This file will be stored as

    A1234 56789 0qwer tyuio p

    You can see that the data chunks from the two files are different.  Hence, there is no dedup.

  • ssholl's avatar
    ssholl
    Level 2
    11 years ago

    ok thanks for that. not quite what i was hoping it would be but ill just see how it goes over the next few weeks