Softek Replicator 2.1.2

Continuing our tour of Exchange back-up systems, Softek Replicator is hardware-independent and uses a device driver that intercepts data to be written to disk. The driver then manages writing the data to disk and transferring it to a target server.

These data pairs are mirrors of each other. In fact, Softek uses a journaling technique to store updates that might leave the mirrored pair replicated incorrectly.

Softek pays special attention to transactional commitment in the relational database sense because its driver notifies applications when transactions are complete. Softek Replicator can operate in asynchronous, synchronous or near-synchronous modes. The synchronous mode won’t return control to an application until the primary and mirrored devices have been successfully written to.

Asynchronous mode will wait until buffers fill to transmit. We couldn’t find tuning points that optimized this without losing messages. The near-synchronous mode is a trade-off that lets a pre-defined ceiling be established before Softek Replicator makes an application wait until records have been written to the primary and mirrored pair servers.

Softek Replicator doesn’t automatically start a mirrored server recovery of Exchange. It might not even know that the primary site has been blown to bits.

Recovery to availability of Exchange2000 or Exchange 2003 required that we use a manual restoration with the Exchange recovery utility. We started Exchange 2000 or 2003, then started the recovery process of the database (message store) and transaction logs. All of Exchange’s components must be on a volume that is not used for paging (such as the ‘C:’ volume of most every Exchange server) because Softek Replicator can’t mirror that volume.

Custom tools and scripts will have to be built by the user/administrator to 1) detect the state of the back-up server, 2) automate the process of terminating the replicant pair’s relationship, and then 3) restore Exchange server in an orderly manner.

For the full report, go to https://www.nwfusion.com/reviews/2004/0503rev.html