9.1 Minimizing risk

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Hardware failures, software failures, human error, and sometimes even natural disasters can disrupt your e-mail environment. Disasters happen, and you must be prepared to respond quickly. By using the following practices, you can reduce the risk and impact of potential disasters.

• Ensure that circular logging is turned off for all Storage Groups. With circular logging enabled, transaction logs are overwritten to save disk space. However, overwriting transaction logs prevents the overwritten logs from being used during recovery operations.

• Perform daily full (normal) backups of the Exchange Information Store.

• Perform periodic full backups of Windows and Exchange configuration data.

• Select server-class hardware for your servers rather than high-end desktop systems. Redundant power supplies, multiple processors, and hardware RAID are worth the extra cost to ensure server availability in the event of a component failure.

• Install all Exchange servers in a controlled environment consistent with the manufacturer's recommendations. Protect the servers with Uninterruptible Power Supplies. Physically secure the environment that houses the servers.

• Protect databases using hardware RAID-5 (disk striping plus parity) or RAID 0 +1 (disk striping and mirroring) technology.

• Keep transaction log files on separate hard drives from the databases. Protect the log files using RAID-1 (disk mirroring) technology.

• Keep the Windows operating system files on separate hard drives and protect them using RAID-1 (disk mirroring).

• Ensure that your Exchange servers have adequate disk space, including sufficient space to support recovery operations.

• Have multiple Windows domain controllers (DCs) for each domain to provide redundancy in the event of a single failure. Three DCs are recommended. If you only have two DCs, then you are at risk whenever you take one DC offline for maintenance. With three DCs, you are still protected if one of the DCs fails while you have one temporarily offline for maintenance.

• Maintain up-to-date documentation for your server configurations.

• Have a dedicated recovery server with the same configuration as your production servers. A dedicated recovery system is one that is only used when a disaster occurs. The server is not connected to the network.

• Fully document your recovery procedures and regularly practice disaster recoveries.

By following these practices, you can reduce the risk and impact of disasters, but you cannot completely avoid disruptions.

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