High-availability Exchange made easy
Azaleos and Teneros appliance-style solutions provide maximum uptime with minimal painFollow @infoworld
Unlike the Azaleos OneServer, the Teneros ACA (Application Continuity Appliance) 2500E does not replace a customer’s existing Exchange server. The appliance sits in between the existing Exchange server and the network backbone. It has a built-in four-port network switch. Two ports connect to a LAN switch, optionally configured for port aggregation (Cisco EtherChannel, for instance). The Exchange server connects to the other two ports.
Setup was remarkably simple. Plug in the appliance, and move the Exchange server’s LAN connection(s) to the appliance’s dedicated ports. Initial configuration is performed using an LCD console on the 2500E’s front panel with a few simple buttons. After entering basic information such as IP address, netmask, and gateway, the remainder of the setup is done using a Web browser from a workstation.
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.
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.