Basics of an efficient storage structure for Microsoft Exchange (page 3 of 3)

To avoid complete resynchronisation it is advisable to deploy an intelligent fast resynch technology as provided by some advanced snapshot solutions. A data change map is used to ensure that only modified data is written to the snapshot volume. This saves a great deal of time compared with complete volume synchronisation, and makes sure that all parts of a mirror match completely.

Snapshot and off-host procedures are ideal for backing up Exchange databases. An off-host server backs up a detached mirror and thus reduces the load on the Exchange application server.

Recoverability
Point-in-time copies are not only the basis for off-host backups of the entire data set but are also used for fast recovery of corrupted or lost data without the time-consuming process of loading the last backup from tapes.

While the Exchange database is running, a scheduler controls the automatic creation of multiple point-in-time copies on online storage media at defined intervals. In the event of a logical error in Exchange, administrators initiate the recovery process on the basis of the point-in-time copy using the last correct data set before the error occurred. Then the transaction logs are automatically applied to guarantee data integrity.

Users should be aware that this quick recovery procedure cannot replace daily backup to tape. Still, it is an excellent additional way of reducing the loss of data and the time needed to recover it during critical business periods without jeopardising operations.