In August of last year, IBM announced its new System i Capacity BackUp Editions [2] (CBUs) that reduced the cost of a second system for business continuity by 30 to 50 percent.

The CBUs promised to be less expensive, more flexible, and generally more customer friendly than similar previous disaster recovery options from IBM. Fast forward to 2007, and it appears that IBM made the right move.

"Comparing the old CBU models to the new, it's just like night and day — IBM has really hit the nail on the head from a pricing, functionality, flexibility perspective," explains Stan Staszak, director of System i/x products for Sirius, which is one of IBM's largest System i value-added resellers.

"The old CBU models . . . we sold literally two or three at the most, and it was just because they were so limited. It was strictly for DR," he says. "Customers could only use them if they were going to experience more than four hours of downtime. They couldn't use them for managed availability, and you couldn't test your HA strategy."

Instead of selling two or three, Staszak says Sirius has sold dozens, which is a pleasant — and massive — uptick.

Flexibility Is King

The new CBU Editions come with a set of standby processors that can be used at no charge in the event of a disaster. The editions let you role swap operations as needed or individually activate the operations to support additional applications. Although this latter feature means you'll have to pay to activate the handy processors, at least you have the opportunity to do so. Plus, the entire box is less expensive than previous iterations.

In response to System i customer requests, IBM now also lets you temporarily transfer your licenses for i5/OS from your primary system to the CBU Edition to avoid incurring extra fees when scheduled or unplanned outages occur.

Staszak says 90 percent of the CBUs that go out the door are intended to be dedicated to high-availability usage, but he offers this metaphor for thinking about more of the possibilities:

"Somebody in Rochester told me this, and it's a good way to think about your OS and your enterprise enablement and licensed program products: You have a driver's license, and that lets you drive any car. You can have two cars in your driveway, but you can only drive one car at a time — that's essentially what this CBU box does for customers. It lets them effectively do a soft license transfer from the primary to the target CBU box, do the role swap, complete the testing or upgrade the old box . . . and then transfer everything back over again."