Storage /

Should you purchase storage on as-needed basis?

By Anne Skamarock
Network World Storage Newsletter, 01/22/01

Over the last couple of months, you have heard me support the benefits of aggregation in storage-area networks and network-attached storage environments. Aggregation allows businesses the freedom to purchase storage as they need it, rather than purchasing storage before it is needed. But is there a viable financial case for purchasing storage on an as-needed basis, or will it cost companies more in the long run?

A reader of this newsletter, Wally Danielson, a capacity planner for a large transportation company, does not think the buy-as-you-go method for acquiring storage will work in his company. He admits that most of his duties are based in the mainframe environment with a " capacity planning department [that] has its act together, " buying disks once a year. " We're still struggling to get a handle on our open systems storage acquisitions, " Wally says.

I cannot pretend to be a financial adviser, but Wally brings up some good points worth discussing. His first objection to buying storage in many small increments (less than 500G bytes each) is that many companies offer volume discounts for larger purchases. That is a very good point. Companies like EMC and IBM will give deep discounts to customers buying very large raw capacities. They are, in effect, passing on some of the volume discount they get from their disk vendor. Wally's company purchases about 1.5 terabytes of storage at a time for its mainframe and puts out a request for proposal for that purchase - which he feels promotes vendor price competition as well.

This policy works well in the mainframe space, where the market is mature and captive. In the open systems environment, this type of buying profile can provide discounts as well.

But I have two points of caution for IT professionals making bulk storage purchases for open systems. The first is, be sure to determine what the business technology needs will be over the next year. In the open systems world, technologies are changing and advancing so quickly, you must ask yourself, can your business afford to be virtually locked out from these advances for a year? The second point to consider is, what is the cost to purchase capital assets? Not every company can afford to purchase storage at the volumes that would bring deep discounts. In this case, the ability to take advantage of the price erosion of capacity over the course of a year, buying as your business needs dictate, is a benefit.

Wally's second point centers around the problems associated with upgrading existing disks and managing storage from multiple vendors with different performance characteristics.

" The most important is the high upgrade costs due to vendor lock-in, " he says. " It is also difficult to have disk devices with widely varying performance capabilities. Invariably the device with the most capacity is the one with the wrong performance. Managing this becomes a nightmare. "

We all know that change happens slowly in large environments. The value of aggregation combined with virtualization, provided by companies such as DataCore, is the ability to abstract the storage from the application host. This abstraction basically removes the vendor lock-in issue and eases capacity/performance problems, distilling storage to its basic performance capabilities. Management is then based on the quality of service required by an application, rather than how much capacity is available on what disk. I will be the first to admit that the management of a networked storage environment, especially in a SAN, isn't where it could be - but it is getting close.

Finally, Wally has the universal concern: " What do you do when an application's performance requirement changes? Move all the volumes to the 'right' device? " My answer to him is yes. The ability to aggregate storage within virtual storage pools allows data migration from one class of storage to another, without the application's knowledge. The application continues running while the business enjoys the benefits of higher performance.

The way companies handle the financial aspects of capital procurement varies with every business. It may be that buying capacity as it is needed does not make sense within your business purchasing infrastructure, or maybe it does. Either way, the ability to aggregate and virtualize storage will ease and simplify the addition and retirement of storage in your data center.

I would like to thank Wally for his ideas and contribution to this newsletter.