Stratus Upholds Reputation For Fault Tolerance

Suitable for e-commerce, public safety and computer-aided dispatch, contact center, point-of-sale/electronic-funds-transfer and infrastructure applications, the ftServer 5240 can be configured as a one- or two-way server running 2.4GHz Intel Xeon processors. The server runs the Microsoft Windows 2000 Advanced Server operating system, so service and maintenance are easy.

The server prevents downtime and data loss by eliminating single points of failure and by providing hardware failover. Because the unit comes as one complete package from Stratus, networks running on a Stratus ftServer are less apt to be plagued by problems such as faulty device drivers and hardware and software incompatibilities.

Stratus' ftServers run Windows 2000 applications unmodified. Applications don't require any clustering modifications to operate in a fault-tolerant fashion, since any Windows application that runs on an ftServer 5240 essentially becomes a fault-tolerant application. Servers can be ordered either with or without a factory-installed operating system.

The CRN Test Center received its sample unit already installed in a heavy-duty cabinet. However, the same hardware can be ordered individually for installation in an existing rack.

The fault-tolerant server is based on CPU modules designed by Stratus. The ftServer 5240 can be configured as a one- or two-way server. One-way units contain two modules, each of which houses a single CPU, while two-way units contain two modules, each housing two CPUs.

The modules run in lock-step, each doing the exact same thing. If one module encounters a problem, it transparently shuts down and puts the server in a call-home mode that will prompt it to notify the appropriate technician.

Once a module shuts down, fault tolerance is gone. That's why some customers go so far as to have their servers configured for triple redundancy. Such a configuration would contain three CPU modules all running in lock-step. Should one of the modules shut down, two will continue to function, thus maintaining fault tolerance.

In rare cases when a Stratus server has a failure, the most effective configuration is to have the server contact Stratus technical support directly. If Stratus is unable to correct the problem remotely, the necessary replacement parts will be sent to the site overnight. According to Stratus engineers, replacement parts often arrive at a customer's doorstep before the customer is even aware of any problems.

The server contains modules other than those for CPUs, such as modules for I/O and storage. The server contains at least two of each type of module. Each module has indicator lights on the front panel to warn technicians when a problem arises. If the server is not configured to notify anyone off-site about potential problems, the indicator lights may be the only way for technicians to know a problem exists, since the server will continue running no matter what.

The ftServer 5240 features two stand-alone Web server cards designed by Stratus. The cards come complete with a modem and wireless connectivity features that allow them to make a distress call if something fails. The Web server cards will keep running even if the server crashes completely, so the ftServer 5240 can "phone home" under any conditions.

Fault tolerance adds more benefits than meet the eye, even though zero downtime is always the desired goal. For instance, a technician can disable one module to perform BIOS updates or maintenance and then bring it back up,and do the same thing with the other module,without causing any downtime.