I'd like to try out the features in your new ONTAP release, but all my systems are in production, and my boss won't buy me hardware just so I can experiment.To solve this, we released the "ONTAP Simulator". The simulator is a complete version of ONTAP that runs as a process under Linux. Instead of using real disk drives, it opens files with names like disk.1, disk.2 and so on. Instead of having a real network card, it hijacks the Linux Ethernet driver to grab the raw packets. (Any customer can download the simulator for free from the Simulate ONTAP web page.)
This is a great tool for learning about ONTAP. Try a new feature, or try different features in combination to make sure they work as expected. You can even delete one of the disk files to see what happens when a disk fails, or edit the disk file with a binary editor to see what happens when there is random disk corruption.
We also use the simulator in our training classes. We no longer need thirty systems for thirty students. We use a couple of real systems—for things like swapping a disk drive, where you absolutely need the real hardware—but mostly students use the simulator. That cuts down on noise in the classroom, saves power, and reduces shipping costs for offsite classes.
At first people just played around, but some customers have gone way beyond that. They use the simulator to verify complex configurations involving multiple systems with clustering, remote mirroring and long-term data vaulting—all with multiple ONTAP simulators running on a single Linux PC. Customers tell me that it's much faster and easier to find configuration errors with the simulator than it would be with real hardware, and they can do it before they buy and install the real hardware. People also use it to get comfortable with a new release before upgrading, to verify that it works in their network environment and to test out their management scripts. Customers have even found ONTAP bugs. Except for low-level drivers, the simulator runs exactly the same code base as production ONTAP, so you see exactly how a real system will behave. (There are some differences: the simulator is slower, it has a hard limit on disk capacity, and we don't have simulated Fibre Channel drivers, so for block storage you have to use iSCSI.)
The simulator is as old as ONTAP itself. As a small startup, we created the simulator before we had any real hardware. Later, engineers found that it was often faster and easier to fire up a simulator than to download a new OS to a real system. Also, the debugging tools were better for a local process than for systems. We used the simulator in engineering for almost 10 years before anyone figured out that it would also be a great tool for customers.
At this point, many thousands of customers have downloaded the simulator. Maybe we've lost a few system sales as a result, but I'm sure that most of those people wouldn't have bought extra hardware just to "play around". Besides, I believe that anything we do to help system administrators to get comfortable with our storage systems is a benefit in the long run, even if we do lose a few sales in the short run.
As far as I know, NetApp is the only storage vendor with anything like this.

