4.001: when you say tiering, do you mean degradation?

(Wow, has it really been 4 years since I started blogging?)

Hu Yoshida posted yesterday a perspective on the evolving meaning of the word "Tiering," presumptively as a context for making a cost- and performance-benefit argument for Hitachi Dynamic Tiering (HDT), as implemented on the VSP.

After the usual Hitachi riff about external storage and thin provisioning pools, Hu turns to a discussion of "Page level Dynamic Tiering with HDT." Here he highlights that HDT moves data in 42MB pages, allowing for relocation at the sub-device level based on utilization of the page(s).

Hu then makes a not-so-subtle attempt at asserting superiority against competitive implementations (e.g. VMAX FAST VP, I suppose), with this claim:

The VSP was architected to address this additional load with a global pool of quad core Intel processors that is tightly coupled across an internal switch matrix to a global cache and front/back end processors. Storage systems that do not have this extra processing power will suffer some performance degradation when they do sub LUN level tiering. (emphasis mine)

Folks, permit me to inject a dose of reality…if anything suffers degradation when auto-tiering, it is the VSP…