The customer disconnect between what they need – I/O – and what they buy – gigabytes – is boiling over in the storage world. Hitachi Data Systems’ always thoughtful Hu Yoshida had a couple of posts whose juxtaposition crystalized the problem. The first post noted, in reference to Web 2.0 companies and the disk drive’s 50th birthdary, that

A great debt is also owed to the engineering innovations . . . which drove the cost of random access storage from about $50,000/MB to less than $0.002/MB. Storage is now cheap enough to give away freely and still cover costs and make a profit based on the services they provide from the stored content. [emphasis added]

Then, in an earlier post on industry revenues, he talks about storage consolidation:

. . . the growth rates for external disk storage have increased to about 60% over the last two years, while utilization of storage has been dropping to about 30%. . . . The CIO of a large financial company with over 2PB of storage said that his storage was only 20% utilized, and over 70% of it was expensive tier 1 storage.

Expensive, underutilized asset or cheap service?
Both observations are true. Both are in dire conflict. Yet it is a weak mind that can’t hold two opposing ideas at once. So what does it mean?

Two illusions
Economists refer to the money illusion, a term for an individual’s belief that a larger number of dollars means being richer, even if inflation is eroding the value of those dollars faster than the value increases. Individuals look at the number of dollars they have, not their purchasing power, and they get fooled thinking are better off even as their purchasing power declines.

In storage, the capacity illusion reigns supreme. We measure storage utilization by looking at capacity in gigabytes, which, as Hu points out, is the cheapest part of storage. The expensive storage component is I/O. And the expensive management component is people.

Run the numbers
Five years ago, the average disk drive cost about $4/GB while the average cost of OLTP tpmc was about $20. Today, 3.5″ disks are about $0.30/GB and OLTP tpmc is about $4. So capacity is less than 1/10th the cost of five years ago, while I/O is about 1/5th the cost. The relative cost of I/O has doubled in the last five years.

Go 1,000 miles between fillups!
The bursty nature of most I/O means that storage systems have to be over-configured to meet peak traffic needs. So the complaints Hu hears from customers have an underlying cause: arrays are configured to meet I/O requirements, but customers buy gigabytes, not I/Os.

It is as if people bought automobiles based on how far they go on a tank of gas. Everyone could tout a bigger gas tank, but the real issue is mileage. Likewise, everyone touts capacity, but I/O is the issue.

It is past time for vendors to change the conversation from gigabytes to IOPS. This would help the big iron vendors sell more big machines, while focusing customers on the I/O demands of their applications. It isn’t the whole solution, but it would be a good first step.

Comments welcome, as always.