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Does anyone know how Retrospect for Mac 9.0.2 works with Data Domain and its cleaning process? Specifically, if I have Retrospect groom backups does that notify Data Domain that it can clean up that space and reuse it?

 

Any guidance or help would be appreciated.

 

thanks

 

Bart

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Data Domain is an enterprise level deduplication storage environment provided by EMC.

 

http://www.emc.com/backup-and-recovery/data-domain/data-domain.htm

 

In our case Data Domain is a member of a media set (the only member). Data Domain only stores to its drives byte level data that is different. For example, if you have 2 servers, each of which is running Windows Server 2008 R2 only the bytes that are different between the two server would be stored. In our case we see data reduction in the 70 - 80 % of original. Data Domain has a "clean" option where it can reclaim storage space that is no longer needed.

 

My question is, if within Retrospect we groom our backups, does it communicate with Data Domain and say that it is no longer needed and therefore can be cleaned from the backups. If you (or anyone else) have further information I'm listening intently.

 

thanks

 

Bart

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I can only offer an educated guess (after reading the EMC data sheets).

 

When a file is altered or deleted during grooming, then EMC Data Domain handles that just fine. I mean, if EMC Data Domain should restore old versions of files or deleted files then it would be a really bad system.

 

Then we have the question about archiving/retention. It looks like you can set up how long EMC Data Domain should retain a file after if has been deleted from the source. Do you use retention at all?

If not, the files should be cleared automatically when deleted from the source. I mean, If it never did that, the EMC Data Domain disks would fill up very fast.

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@Lennart: Thanks for always being willing to tackle new subjects with logical responses. :-)

 

@MuleMan: We highly recommend Data Domain products for reliable, destination-based dedupe of Retrospect backups. Because Retrospect's disk-based backup archives are stored in 600 MB container files, and because the files in the backup are written into these container files without being altered*, dedupe runs just as well as were the files stored natively on the DD hardware. Retrospect's grooming process deletes old container files and replaces them with new files, so Data Domain's dedupe routines handle this situation perfectly.

 

*In you require that your backups be encrypted: The most important thing when using hardware-based deduplication is to use the dedupe array's encryption feature, NOT Retrospect's. If you use Retrospect's encryption, then you'll significantly reduce the effectiveness of the hardware-based dedupe capabilities.

 

Cheers,

Eric

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Thanks to both of you for excellent feedback. I feel very comfortable with your comments that all is well in our Retrospect / Data Domain world!!

 

Bart

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