A technical paper describing the Flexible Volume architecture was presented at USENIX '08 in Boston in June. The paper describes FlexVols in ONTAP that support dynamic creation of right-sized data containers that can be resized (grown or shrunk), snapshotted, cloned (producing multiple writable shared unmodified data instances for efficient multi-use "copies" of data), and mirrored for disaster recovery. These features are part of our storage virtualization technology.
FlexVols evolved naturally in WAFL, from its original single volume, single RAID group design by Dave Hitz going back to the beginning of NetApp. Over the next few postings (I really do need to pick up the pace here on blogging) I want to explore some of the features and evolution of this core technology to our storage products.
From a technologist's viewpoint, what has struck me fundamentally about the design and implementation of WAFL has been its remarkable ability to evolve in an upward compatible way to take on new features and enable new capabilities since its inception. Prior to joining NetApp in January, 1994, I was at Sun Microsystems where I was a bit involved with discussions on file systems directions at Sun. I remember being struck by the impression that WAFL at that time had many of the things we were looking for in a new file system for Solaris.
Technology is interesting. You see the end result and sometimes marvel. But technology doesn't create itself. People create technology. Looking at the arc of WAFL technology over my time at NetApp I see three distinct phases from Dave's original design, to a multivolume, multiraid implementation led by Blake Lewis, to the FlexVol architecture led by John Edwards. After Dave's initial work, the development of WAFL grew to include many contributors.
The biggest reason I stay at NetApp is the pleasure of working with truly talented developers and shipping innovative product to our customers. It's a lot of fun!
We are going through some exciting times in the storage industry. The storage virtualization capabilities of ONTAP are proving to be a key enabler for re-architecting data centers around application server virtualization. The greatest gains in power efficiency and reducing data center footprint is by taking an end-to-end approach from the application to the storage holding the application and its data. As a technologist I find it interesting that WAFL and ONTAP continue to enable innovative and flexible data center storage architectures and enhance capabilities application provisioning and deployment.
Over the next few weeks I want to describe not only the what, but the why, of the architecture and design of WAFL and ONTAP and how it affected our product evolution.
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