lly fault-tolerant (FT) systems are coming down in price. Customers are starting to expect HA in their servers.
Why HA Now?
According to Donna Scott of the Gartner Group,
the lower costs of HA technology and production, the increasing prevalence of the Internet, and the growth of globalization, mobile computing, and 24-hour, seven-day-a-week customer-service requirements are all fueling the fire for HA solutions.
Where big-league HA solutions used to cost $1 million and up, Unit Systems, an NCR VAR, can now offer top-notch systems ranging from $250,000 to $300,000, says Christopher Radzik, president of Unit Systems. This puts the technology within the grasp of some of today's fastest-growing markets, such as those required by Internet service providers (ISPs) and for companies installing voice-processing systems. Armed with ammunition such as this, companies outside the Fortune 500 are installing HA systems.
Companies and Technologies
Computer vendors have been quick to respond with HA and clustering solutions for the VAR and end-user community. Data General, Digital Equipment, Hewlett-Packard, IBM, NCR, Silicon Graphics, Sun Microsystems, and myriad small
er vendors have taken up the HA torch. Tandem Computers and Stratus Computer lead the pack with FT solutions.
For example, IBM has extended its extensive experience with highly available systems in the mainframe arena to its RS/6000 and AS/400 platforms, where its High Availability Cluster Multi-Processing (HACMP) software brings HA solutions down into the midrange turf. Digital has leveraged its pioneering VAXcluster technology into its AlphaServer line with TruCluster software for Unix and OpenVMS systems.
HP is another solid contender, with its HP-9000 midrange servers and MC Service Guard clustering software. NCR, one of the biggest suppliers of HA solutions, offers midrange solutions using its WorldMark 4300 with LifeKeeper clustering software. Sun, a latecomer to the HA field, offers an HA solution on its Sun 4000 and 6000 enterprise servers. When it comes to FT systems, Tandem rules the roost with its NonStop Himalaya systems. Stratus comes in second with its Continuum series.
Buildi
ng Experience
Server technology alone does not make an HA solution. "Proper administration and maintenance of clustering systems is one of the biggest challenges in the mid-market today," says
Tom Foley
, president of Baystate Computer Group. "You can invest $2.5 million in a sophisticated HA solution but can't expect to administer it with a $45,000 technician. The customer must train, train, and train again."
The Gartner Group's Scott suggests that customers build HA "practices" in their companies. "An HA solution is one-third technology, one-third business practice, and one-third organization," she says. "Organizations must develop proper HA procedures; train personnel; automate wherever possible to prevent user error; implement good testing, deployment, and configuration management procedures; and look at network and systems software that predicts problems," Scott summarizes. "Successful HA is not an out-of-the-box solution. It is a complex formula that must be expertly e
xecuted."
HA vs. FT
The degree of HA needed for each application depends on the risk factors: How devastating is downtime, and how much is the customer willing to spend to prevent it? In most organizations, 99 percent availability is good enough. Even the phone company promises only "five nines," or 99.999 percent uptime.
What makes the difference between 99 percent and 100 percent availability? Clustering technology exists that can achieve a failover swap in less than a second. But what about the transaction in process? You can roll it back and reconstruct it in a matter of minutes. For many companies, this is acceptable. For others, 100 percent availability means nonstop computing, without even a nanosecond of downtime or a byte of data lost. For these solutions, customers turn to FT technology (see the sidebar "Defining Terms").
Traditionally, FT systems have come with the highest price tags. However, improvements in production and technology similar to those that have benefited
HA solutions are making FT solutions more affordable as well. "A business can now afford an FT system at only 30 percent higher cost than an HA-cluster solution," says Jon Howe, who is the chief technical officer at ACI. "As with any technology, we are always pushing the price down over time."
Will the Twain Ever Meet?
As it stands today, HA and FT are two different technologies with two different levels of availability, but most experts agree that the distinction is growing smaller. HA is even cropping up on PCs, as Microsoft comes to market with its clustering solution for Intel-based processors. This will create yet another set of potential markets, driving HA solutions even further down the food chain.
In the near future, we will also see an intermarriage between HA and FT technologies, further blurring the distinction between them. Already, the level and kind of availability that can be created by either HA or FT solutions is approaching a difference of only a few decimal points. Ta
ndem and Microsoft are working together to blend the two types of systems, incorporating Tandem's FT nonstop-kernel philosophy -- hide the failure from the application -- with Windows NT's HA-server philosophy -- failover and restart the application.
But no matter how you slice up the market or define the terms, the driving need for HA systems remains the same. As people in all types of businesses come to depend on their computer systems almost as much as the electricity that powers them, they will be less and less tolerant of outages of any kind. "People won't tolerate the lights going out in their offices for an hour every week," Radzik concludes. "Why should they expect any less from their computer systems?"
Where to Find
Digital Equipment Corp.
Maynard, MA
Phone: 800-344-4825
Internet:
http://www.digital.com
The Server that Wouldn't Die
