SAS or SATA for 3 TB drives?

We are looking to purchase new 3 TB enterprise-grade drives and can buy either SAS or SATA models.

AFAIK, SAS generally gives better performance than SATA, but searching for benchmarks I found the article Seagate Constellation.2 and Constellation ES.2 Hard Drive Review .

The summary is that SATA was actually faster than SAS on most of tests. But reading through comments, it seems there is a feature called "prescan", which was apparently responsible for the low performance.

What can be recommended from a performance point of view, is it SATA or SAS? Is the real-world performance acceptable?

The kind of work-load of our systems is heavy multi-threaded sequential writing and erasing, with occasional random read access.

Answer

I believe that Womble's comment to Peter Schofield is the best observation here...these aren't true SAS disks.

No doubt you're being sold "nearline SAS", which is where they take a SATA disk and put a SAS interface on it. The drive mechanics are identical to the SATA version; only the interconnect has changed.

When you plug a nearline SAS drive into a SAS controller, it will be faster than the equivalent SATA drive because the protocols are different, and it takes a certain amount of time to convert between the SATA protocol and the SAS protocol. Wikipedia says that there can be a 30% increase in speed, but I've never delved into the protocols themselves, so I couldn't tell you.

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As an aside, I really don't know what kind of faith I'd put into those numbers. Storage Review does a pretty decent job, I think, but I can't figure out why they didn't get another drive to test when the disk started performing like this:

http://www.storagereview.com/images/seagate_constellation_es2_3tb_iops_workstation_4k.png

That's a drive that should be physically identical and in terms of interface, should be performing much more in-line with the others. The fact that it shows a discrepancy like this indicates (to me, anyway), that there was something wrong with the device.

They do say that it checks out with Seagate's test suite, but I wouldn't put stock in the results until they're checked against another drive of the same model. Those results are just too weird.

Edit

Since it was brought to my attention that I didn't actually answer the question, my guess is that the SAS drive will give you better performance because of the reasons I listed above. That is what I would go with, unless research bears out the odd results that Storage Review got.