High-availability Exchange made easy

The customer’s existing Exchange server remains the primary server, which is administered as usual. The 2500E appliance replicates mailboxes on a real-time basis. In the event of a failure of the Exchange server, the Exchange IP address is moved to the appliance. If this fail-over occurs, your Outlook users simply see a dialog box indicating that they need to exit Outlook and restart the client; otherwise nothing else is different.

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Unless you’re relying heavily on public folders. These are still usable if you plug a Teneros device into the network, but public folder replication wasn’t yet available in the version 2.8.3 release we tested. Teneros promised that public folder replication would be offered in the 3.0 release that should be available by the time you read this.

Like Azaleos, Teneros provides 24/7 monitoring through its off-site support center, notifying customers of any system problems based on a contact and escalation list the customer provides. Depending on the severity of the problem and time of day, notification can be via telephone, e-mail, or pager. One key difference from the Azaleos solution is that administration of the appliance belongs exclusively to Teneros. Teneros applies all patches and performs any other maintenance. Customers schedule a maintenance window via the solution's Web interface.

One particularly interesting feature of the 2500E is that it contains two independent subsystems, each with its own motherboard and CPU. The main system runs Windows Server 2003 and Exchange Server 2003. The other subsystem, which runs Linux, monitors the Windows system. The Linux system serves as the point of maintenance and patch deployment for the Windows system, and it can recover it in case of errors.

Finally, Teneros offers a Failback function that promises complete restores of the primary Exchange system in case of data loss. If the latest backup is, say, a week out of date, Failback can use the restored data as a starting point and then replicate the most current data, which should result in no data loss. We love this feature because more often then not, when one of our customers asks for help after an Exchange crash, we come on-site only to find that someone forgot to change the tapes for the past few weeks. So we end up restoring data that is at least a week out of date, usually more, making the whole situation that much worse.

As many as 250 users are supported per appliance. The only variation between models is the amount of storage provided for the information store. A base configuration of 50GB costs $15,000; the top end is a 500GB information store costing $22,500. Teneros’ remote monitoring and support cost 25 percent of the purchase price per year, based on a one-year contract. A three-year contract reduces the cost to 20 percent of the purchase price per year. An optional contract for hardware replacement costs $850 to $1,000 per year.

Appliance or Near Appliance

Overall, we were most impressed with the simplicity of the single-box Teneros solution. It provides most of the functionality necessary to keep Exchange going in case of emergency, and requires little care and feeding. What you gain in ease you lose in scalability, however.

The Azaleos OneServer uses Microsoft Exchange clustering, which means it can do more than the Teneros box but only by using a lot more hardware. The basic Azaleos package uses three servers, a switch, and a storage device.

Both companies aim for the same 250 to 5,000-user market, although at the low end of that spectrum Teneros offers much better value. With an entry price three times higher but much greater growth and storage capacity, Azaleos is a better choice for organizations with 1,000 or more users.