The Neverfail system requires an additional NIC in the primary server, and a backup server running the same server OS and the same version of Exchange. Neverfail runs on Windows 2000 Server or Windows Server 2003, and it supports Exchange 2000 and Exchange 2003.
Setup is simple and straightforward. The Neverfail SCOPE (Server Check Optimization Performance Evaluation) utility identifies any performance or configuration issues with the Exchange server and recommends solutions before installing the fail-over software. It takes snapshots of server performance and performs trend analysis to identify areas that may become problems in the future. It also generates a system ID that Neverfail uses to create a license key. After the key has been received from Neverfail, the system clones the Exchange server to the backup system.
The installation copies all application files, registry settings, services, and data stores associated with Exchange, so the backup server is a perfect duplicate, including any software updates, service packs, and so on. The system monitors all the key services, as well as the main Exchange server process, so any problems -- even with associated software or performance degradation -- can trigger the fail-over.
Pricing begins at US$7,600, which includes Heartbeat (the core engine), the Exchange module, and four SCOPE analysis cycles (the initial analysis of the server prior to installation, and three follow-up checks), as well as maintenance for one year. Pricing is per pair of servers, based on the server in the pair with the greater number of CPUs. A low-bandwidth module is available that enables compression and encryption over a WAN link, as well as asynchronous replication. This would normally be used for additional data backups rather than fail-over.
Neverfail is relatively expensive, especially if you have multiple Exchange servers. It is probably less expensive than using Microsoft Exchange clustering, and it's much easier to set up. If you need 24/7 uptime for all e-mail users, Neverfail is a good way to go, although SteelEye's LifeKeeper offers more functionality at a lower price.
SteelEye LifeKeeper
SteelEye LifeKeeper is a server fail-over product similar to Neverfail, but it offers additional flexibility, including scheduling of replication for off-peak hours (or with a 24-hour delay to ensure that store corruption isn't passed on), compression for replication over WAN links, and one-to-many replication to create multiple copies of a single server.
LifeKeeper can run on any version of Windows 2000 or Windows Server 2003. It supports Exchange 2000 and Exchange 2003, and it doesn't require identical hardware for primary and secondary servers. The cost is less than Windows Clustering, at $3,280 per pair of servers, and one standby Exchange server can protect multiple active Exchange servers, although capacity planning will be essential in case all the active Exchange servers fail at once. In addition, LifeKeeper supports shared storage between the primary and secondary servers, which can speed up the fail-over process.
For this review, I tested LifeKeeper 5.3. Setting up LifeKeeper is straightforward. You will need to create service accounts, as with the other solutions, but the documentation steps you through the process. Clients get an error message during fail-over, but clients on the LAN will only need to retry the operation -- restarting Outlook is not necessary. As with Neverfail, users connecting via MAPI or Outlook Web Access may need to restart the client to connect to the backup server.
LifeKeeper provides data compression and encryption over a WAN connection, and it can replicate to a local server for fail-over, as well as to a remote server for business continuity. The LifeKeeper GUI can administer all LifeKeeper clusters in an enterprise via a straightforward interface.
LifeKeeper offers features that Neverfail doesn't, and at a lower price. LifeKeeper's setup is a little more complex than Neverfail's, but this is partly because of the additional features. One interesting extra is the ability to fail over from a physical to a virtual server, or vice versa, although most admins will not be comfortable running mail servers in a virtual environment just yet. Unless you already have an investment in other Neverfail clustering technologies, LifeKeeper is a better deal.