High-availability Exchange made easy

Azaleos and Teneros appliance-style solutions provide maximum uptime with minimal pain

The obvious solution for bringing HA (high availability) to your Exchange server is to use Microsoft’s own Exchange clustering features. Although Exchange’s clustering is reliable and robust, this isn’t an easy configuration to set up. It’s also usually costly, not only in terms of additional hardware and software licenses, but also because it requires a skilled Exchange administrator.

In a large enterprise environment, it’s likely that one or more senior Exchange admins are already on staff, so this approach makes excellent sense for customers of this size. Small businesses with 25 users or less, however, will probably get better bang for their buck by choosing an Exchange hosting service. And midsize companies that need real high-availability but don't have dedicated Exchange administrators on staff might be better served by a mixed approach, recently referred to as “mid-sourcing.”

The Azaleos and Teneros solutions reviewed here fall into the latter category. Both are complete Exchange HA solutions that are installed on the customer’s premises, but managed and monitored off-site. The Teneros product is well-suited to midsize businesses approaching 250 users, whereas the Azaleos product is built to support thousands.

We began the test by building an Exchange 2003 server to act as our existing TestCustomer server. This ran on a Dell PowerEdge 1800 with dual 3.0GHz Intel Xeon CPUs and 1GB of RAM with Windows Server 2003 installed. We also attached a client workstation running Outlook and using Internet Explorer to connect to Outlook Web Access. Our test products had to install in and around this infrastructure, with points awarded for easy installation and a minimum of user interruption.


Boil the Azaleos OneServer down to its essence and you’ll find a full-featured Microsoft Exchange Server 2003 cluster slickly prepackaged into a ready-made solution, although not exactly an appliance. The company shipped us a configuration consisting of three Dell PowerEdge 1850 servers and a Dell PowerConnect 5324 switch ready to be installed. The customer is responsible for providing a network storage appliance (usually obtained through an Azaleos partner) as well as an Active Directory domain controller. For our test, Azaleos loaned us a NetApp FAS270 filer to serve as the SAN resource.

If the OneServer deserves the appliance name, the reason is the Azaleos front-end for e-mail administrators to manage the device. The functionality is all Microsoft Exchange clustering, but the Azaleos interface is much easier to use. The initial configuration is shipped with the system on a USB key, based on information provided by the customer, including an IP address range for the servers and an Active Directory domain name. To keep this simple, Azaleos provided a questionnaire prior to delivery with an easy-to-follow matrix.

If there is an existing Exchange environment, mailboxes and public folders can be migrated to the Azaleos appliance for high availability. Less critical mailboxes or public folders can be left on the existing, nonclustered server, or that server can be removed entirely. According to Azaleos, the setup can be performed by the customer with an installation script or by an Azaleos engineer on-site depending on customer preference.

Setup of the NetApp storage and Azaleos OneServer took us approximately four hours with on-site assistance. One glitch came up where the USB key could not be read by two of the servers. This problem was fixed quickly by our visiting Azaleos engineer but would have required a call to technical support for customers attempting the install on their own. Azaleos recommends working with a systems integrator who will validate the customer’s initial configuration and assist with the setup.

After physically connecting the equipment, the on-site engineer walked us through the initial setup. Each server was booted from the USB key, which ran a configuration script. After the admin node came online, we could watch the progress of the Exchange cluster via a Web interface from a workstation. Each Exchange node came online and joined the cluster. After the setup was completed, what remained was to migrate objects into the new server. This migration is done using standard Exchange tools such as Microsoft Exchange System Manager.

The base appliance configuration costs $30,000 for as many as 2,500 users. Separate from this cost are the storage area network, purchased from an Azaleos partner or some other compatible vendor, and Windows licenses for the cluster, consisting of one Microsoft Windows Server 2003 Standard Edition for the admin node plus two licenses each of Microsoft Windows Server 2003 Enterprise Edition and Microsoft Exchange Server 2003 Enterprise Edition for the OneServer.

The finishing touch is the Azaleos OneStop subscription, which provides 24x7 monitoring and support. The subscription provides remote monitoring and diagnostics. If the customer is willing to provide IPSec VPN access into the network, troubleshooting is also available remotely. Azaleos indicated that built-in VPN functionality is being considered for a future release.

All patches from Microsoft and Azaleos are provided monthly on a DVD. Azaleos recommends disabling Windows Server Update Services and relying on their DVD to ensure that all patches have been tested for the OneServer environment. Optional management features available from Azaleos include support for Exchange mobility services, anti-virus, and anti-spam — each available for an additional fee.

Although it’s a hefty solution, considering that the ‘appliance’ is actually a mini-rack of five separate devices, we very much liked the ease of use as well as the flexibility when it came to integrating the OneServer into an existing environment — even relatively large ones. Because moving Exchange objects is accomplished using the standard Microsoft Exchange System Manager or other Active Directory management tools, things such as public folders and directory integration are readily available to Azaleos users.

The only limiting factor is the amount of disk space for the information store. Because the SAN is provided separately, you can scale it for larger implementations, but this can have a real effect on the overall solution. That said, Azaleos has a great product here, although it’s definitely aimed at the high end of the midmarket spectrum.

TenerosACA 2500E

If you’re looking for a plug-and-play solution for Exchange HA, and users number in the tens to hundreds not thousands, look no further than Teneros. The appliance is a single box that sits in front of an existing Exchange 2003 server and provides real-time replication and fail-over.

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.

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.

InfoWorld Scorecard
Value (10.0%)
Integration (25.0%)
Setup (15.0%)
Features (15.0%)
Manageability (25.0%)
Scalability (10.0%)
Overall Score (100%)
Azaleos OneServer 7.0 7.0 8.0 8.0 8.0 8.0 7.7
Teneros ACA 2500E 8.0 8.0 9.0 6.0 8.0 6.0 7.7