The current rage among vendors and press, at least when it comes to business-continuity planning, is the substitution of a high-availability architecture for conventional disaster-recovery (DR) techniques. CA's acquisition of XOSoft last year heralded the trend, which now finds advocates at EMC (having acquired VMware and Kashya) and elsewhere.
Using "active-active" or "active-passive" clusters to fail over from one site to another isn't a new concept. Companies with deep pockets and a desire for always-on operations have used this strategy for years. However, the price of the solution--which requires not only expensive hardware and software, but also a "hard" or predefined recovery site--typically has put it beyond the reach of less well-heeled organizations.
To hear vendors tell it, all that is changing. VMware's latest ESX Server as well as products from CA and Neverfail Group are moving HA to the fore. However, other factors are also contributing to the trend.
The state of Illinois implemented such a strategy in the wake of 9-11, for example, to work around the reluctance of legislators to spend money on anything called DR. When state IT managers asked for a disaster-recovery budget in 2002, they were rebuffed. However, when they instead explained that they just needed a place to test application changes, and pointed out that the state already owned a building some 50 miles from Springfield as well as the right-of-way between the sites for laying dark fiber, and that for a very small investment they could replicate gear and workload between the two sites, they were funded. Apparently, to get management buy-in on DR, you may just have to call it something else--anything else.
HA makes sense from a business-continuity perspective. It basically enables recovery and builds resiliency into IT architectures--a superior strategy in many ways to conventional disaster-recovery techniques, where the recoverability/resiliency of IT is simply bolted on.