Thinking about purchasing a storage analytics product? Then here's a good first question to ask any sales representatives who call on you. Ask them if their products can tell you how much storage you have in your environment. If their immediate response is yes, thank them for their time and hang up the phone.
What a response like that indicates to me is a complete lack of understanding on their part of what it is you just asked them. Measuring storage capacity in enterprise environments today is no trivial task -- with or without a tool.
Where I work, every month someone needs an answer to how much disk and tape capacity we have and which of it is mainframe or open systems. Even then, those numbers tend to be more subjective than storage managers care to admit.
How do you really measure storage any more, and how do you know which reports are correct? For instance, do you count the disks in EMC Clariions that are reserved for the Clariion operating system and hot spares? If you do include them in the totals, then how do you explain the extra capacity, and if you do not, then is the product doing its job?
Equally frustrating is reporting on tiered storage environments. For what does 5TB of free capacity mean? Without knowing what type of disk drives it resides on, what storage arrays it is in and what server operating systems it's compatible with, is the information any good? And is that usable or raw?
Quantifying what you have in your environment sounds wonderful, but don't fall for the hoopla. Start small and grow slowly with these products because everyone is probably a ways off from knowing exactly what they want these reports to produce.
Jerome Wendt is a storage engineer and storage analyst