Deduplication on NetApp

I found that there are always multiple realities to deal with when looking at new technologies. There are the excited implementors, who make it sound good. There are the sales people who say what you want to hear, and thier are the Technical Reports that tell you what it really does. I’m just picking on NetApp in this post, but this is true with any new technology, so while you might learn a lot of good stuff from your sales friends make sure to ask for links to the white papers or TRs in NetApps case.

Deduplication is a great benefit for storage admins out there today, it helps us to reclaim some of that expensive and ultimately wasted space that may be on our storage environments. The largest impact I’ve seen in in virtual environments with multiple VM’s with the same OS. The can bring savings of up to 50% or more. On the other hand CIFS shares you may only see savings of maybe 10%. There are some limitations and planning that should go into this. One being performance hit during the dedupe operation on some applications, the other being size limitations of your volume. So in cases where you want to more performance or space and still dedupe you may need to look into a different NetApp Model, newer version of DataOnTap, or even a PAM card. If these all do not meet your needs or cost to much then we may have to pass on the dedupe for that volume.

Below are just some highlights I found useful, but please read the TR from NetApp as this may change over time.

Benefits:

  • Saving space on your storage network as much as 50%
  • Three easy ways to dedupe, schedule, auto, and manual
  • Deduplication does wonders for large virtual VMDK files, and just large files in general on NFS shares
  • With NFS the savings is passed onto vSphere just remember to refresh the volume datastore stats

Limitations:

  • Limited Volume size based on Data OnTap version and NetApp model.
  • Snapshots taken before deduplication are locked, and take up aditional space, this is not true for Snaps taken after a dedupe job.
  • Some types of files just do not dedupe that well especially the really small ones, and images.
  • See the TR referaced below for more information

Reference:

http://media.netapp.com/documents/tr-3505.pdf

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About Paul Cardelli, CISSP
Cyber Security Analyst, and computer guru

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