According to Gartner Group, 80 percent of business people say they consider e-mail more valuable than the phone for business communications. Gartner also estimates, however, that most small and midsized enterprises experience more than 40 total hours of unplanned e-mail downtime each year, which can translate into significant financial losses.

E-mail has fundamentally changed the way business is conducted, and reliance on this pervasive form of electronic communication is only expected to grow.

E-mail has fundamentally changed the way business is conducted, and reliance on this pervasive form of electronic communication is only expected to grow with the spread of mobile devices for business uses. Meanwhile, solutions to the e-mail downtime challenge may not be obvious. Is affordable five-nines e-mail uptime possible? Can downtime of any kind be prevented–even for routine maintenance?

The good news is that IT pros looking for reliable and cost-effective e-mail continuity solutions have a number of options. The most common e-mail continuity solutions in the market today are for Microsoft Exchange, falling into the following categories: Microsoft clusters, software replication solutions, hosted disaster recovery and remotely managed failover appliances.

Clustering, in which a group of servers, as few as two, work to protect each other, can be used for a variety of applications, not just e-mail. Their downside is their normal complexity and expense to set up and maintain. Clusters require additional servers to be installed, set up and synced with the primary e-mail server. All of the servers in a cluster must be maintained at the same patch and revision level as the primary server, so the ongoing maintenance burden is increased. Furthermore, ongoing maintenance requires cluster-certified IT staff.

Software replication solutions are software-only packages, often requiring additional servers, operating systems and application software to clone the primary server. The operating systems, Exchange server software and vendor software are installed to replicate the data. Additionally, software agents must be installed and maintained on both the primary Exchange server and on all of the desktop/laptop computers of the e-mail user community.

The agent software can be destabilizing to both the Exchange server and the e-mail infrastructure. Plus, the ongoing maintenance to patch and update both the server and desktop/laptop client agents can be cumbersome and time consuming.

RISK OF E-MAIL DATA LOSS

These software solutions blindly replicate the data at the block or file level, so they also replicate data corruption, which is a common failure cause of downed e-mail servers. Furthermore, failover is not immediate, and failback can result in e-mail data loss, which is a risk most organizations cannot afford.

Lastly, software replication solutions can also be out of the reach of smaller IT departments because installation is complex and ongoing maintenance can double or even triple the overall IT workload.

Hosted disaster-recovery solutions, as the name implies, replicate e-mail across the Internet. While they require fewer ongoing IT resources than clustering or replication solutions, they can be expensive, and they do not provide recovery from a corrupt database, which can occur two to three times per year. Hosted disaster-recovery solutions also take two to four days to install, and can put potentially destabilizing software agents on all e-mail severs and on the desktops/laptops of the e-mail users.

These solutions offer no high-availability support for LAN failover caused by a local server failure. They are used for disaster-recovery scenarios when the entire site where the primary server resides goes off line. Furthermore, transparent support for mobile devices and continuity for complete Outlook client functionality is generally not available.

International legal and financial services organizations, which have high levels of messaging activity at all hours of the day, are examples of the companies most challenged by continuity planning. Their e-mails often contain proprietary and critical communications, such as contracts or portfolio information, and they rely heavily on the accuracy of time and date stamping.

These types of companies often have fewer employees than companies in other industries with comparable revenue, so their IT staff may be small. Therefore, adding task burden to the already time-consuming support of their e-mail ecosystem is unacceptable.

The key to selecting a continuity solution is outage avoidance. This means that the solution must assure protection against both local server failure and a full site outage for the application and all of the data. A new approach to e-mail continuity for Microsoft Exchange is low-cost, high-availability and disaster-recovery application continuity appliances.

EASY TO INSTALL

These appliances are essentially "plug-and-go" because they take less than 20 minutes to install, require no special training or IT expertise to operate, and require no ongoing maintenance. The appliances are remotely monitored, patched and maintained by the vendor's network operations center. These appliances provide instant failover, protect MS Exchange both locally in the event of a server outage and remotely for disaster recovery in the event of a full site outage (the data remains safe within the security of the company's network).

Disaster-recovery application continuity appliances enable companies to deploy comprehensive, cost-effective e-mail continuity by protecting mission-critical Microsoft Exchange servers. They assure 24/7 end-user e-mail continuity for both the Exchange application and corporate e-mail data, in the event of planned or unplanned server or site outages.

When an Exchange server fails or an entire Exchange site goes off-line, the appliances will take over e-mail operation from the downed Exchange server or site. All e-mail data, from before and during the outage, is preserved on the appliance and can be replicated back to the updated, repaired or replaced Exchange server, while end-users continue to have full e-mail functionality and data access.

Some appliance models can support partial as well as full mail store replication back to the Exchange server, allowing simple protection against commonplace site-level outages such as power or network failures. They should also transparently handle "split brain" events from site outages by automatically reconciling the divergent Exchange mail stores without any data loss.

Because the Exchange mail store within the appliances is always operational and data replication and automatic verification are continuous, organizations are protected from discovering mail store corruption at the time of a disaster. This important protection is not available, however, from products that rely on sequential byte-level replication or log replay technology. These appliances can be deployed on the LAN for high-availability protection, or in a remote site for disaster-recovery protection of the Exchange server, ensuring application continuity and data integrity for mission-critical e-mail communications.

Andréa Skov is vice president of marketing for Teneros, Mountain View, Calif.

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