Your network topology is excellent. You have all of the latest, high quality hardware and your monthly software maintenance and update schedule is planned and executed with military precision. However, you still have to schedule downtime for server maintenance, notify the entire company, and listen to their collective groans. And, as always, you have more IT tasks than hours in the day to complete them in.

This is a typical scenario within many IT environments; maintenance, upgrades and the addition of new hardware and users are mapped out with care to minimize interruptions and make the most of your staff's time and resources. Then, out of the blue, the mail store gets corrupted and your Exchange server crashes.

This is not atypical of an IT professional's work environment. These talented, dedicated professionals work long hours behind the scenes to assure that the local and global corporate services stay up and running, smoothly, efficiently and consistently.

Continuity of mission-critical infrastructure and applications is one of the biggest challenges they face, and the number one mission-critical application is email. When it fails, access to an estimated 60 percent of corporate data is cut off and everyone from the CEO to the front-desk receptionist is immediately aware of the problem and starts yelling. IT is then typically burdened by numerous calls from users unable to access their email, further compounding the problem and limiting the capacity of the team working to resolve the issue.

Companies today rely heavily on email to conduct their business and can lose thousands, even millions of dollars in productivity by a single day without access to this essential communications tool. Implementing an email continuity solution has been proven cost effective compared to the very real costs of even a brief loss in connectivity.

So, with the variety of marketing promises for 24 X 7 faultless continuity solutions, a fixed budget, and no time for added tasks, how do you evaluate the options for dependable, cost effective, mission critical application continuity?

There are six key questions to ask that are critically important when considering a continuity solution for Microsoft Exchange. These questions are important because many of the so-called high availability and continuity products actually destabilize your network and proliferate data corruption when your Exchange server fails, adding to the workload of the already overburdened IT staff.

The questions are simple and the details are important so make sure you get past the marketing hype to the honest detailed technical answers. Look your vendor in the eye and ask:

1. Does the product place intrusive software agents on my Exchange server? (For your peace of mind and the stability of your network the answer must be no!)

Many continuity products install drivers, operating system services and/or other software on the Exchange server. The drivers are installed to intercept and capture disk block level writes. The services have write access to and perform operations on the Exchange mail store and configuration.

2. Does the product make ongoing modifications and configuration changes to my Active Directory and DNS? (Again, for the stability of your network, the answer must be no!)

Most continuity solutions make continual, automatic modifications to your Active Directory during both failover and failback. These third-party modifications are extremely risky to the stability of all of the Microsoft infrastructure applications running on your network and dependent on Active Directory. Destabilization of Active Directory can cause these applications to crash.

3. Will Exchange database corruption be replicated on my Exchange server? (If you do not want to explain to everyone, from the receptionist to the CEO, why their email has disappeared from the Exchange server, the answer must be no!)

Most Exchange continuity solutions replicate database corruption to the backup server. Furthermore, backup servers that share a data or mail store device are completely disabled in the event of database corruption. These products copy at the block, file or byte level and cannot detect Exchange database corruption when running in real time. Therefore, the vendors of these products recommend that you run the secondary server data replication a half hour behind the primary server to minimize the possibility of data corruption. The half hour delay produces a data loss window during which time email can be truly lost and irretrievable. And, despite the delay, corruption can still be replicated on the secondary server.

4. Is Failover truly instant or a 10-30 minute downtime window for my end users? (If you don't want to spend budget money and your precious time installing a continuity solution that "almost" provides continuity, and then still have to cope with all of the employees screaming at you that their email is down, then the answer must be instant failover!)