ZFS: To Dedupe or not to Dedupe...


...that is the question.

Ever since the introduction of deduplication into ZFS, users have been divided into two camps: One side enthusiastically adopted deduplication as a way to save storage space, while the other remained skeptical, pointing out that dedupe has a cost, and that it may not be always the best option.

Let's look a little deeper into the benefits of ZFS deduplication as well as the cost, because ultimately it boils down to running a cost/benefit analysis of ZFS deduplication. It's that simple.

ZFS is for 1337 Hax0rz


The developers of ZFS are a funny bunch of people. You can tell that by watching the "ZFS: The Next Word" talk, meeting them on conferences, reading their blogs or their comments on mailing lists.

And there are also some funny parts in the ZFS source code, too. In fact, if you use ZFS, you'll have a funny joke sitting on your disk, right under your nose!

I was reminded about this particular joke while listening to Ulrich Gräf's excellent talk on ZFS internal data structures during OSDevCon 2009 (watch a video of Ulrich's talk here).

But first, we need to dig a little bit into the world of ZFS data structures.

OpenSolaris ZFS Deduplication: Everything You Need to Know

Deduplicaed Folders Illustration

Since November 1st, 2009, when ZFS Deduplication was integrated into OpenSolaris, a lot has happened: We learned how it worked, people got to play with it, used it in production and it became part of the Oracle Sun Storage 7000 Unified Storage System.

Here's everything you need to know about ZFS Deduplication and a few links to help you dig deeper into the subject: