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Survivor's Guide to 2006: Storage and Servers: Page 4 of 14

In 2005, some big-name hardware and software vendors threw half-completed products at you, claimed no one else did replication or continuous data protection for their target market and asked you to swallow that lie whole. In 2006, those vendors will catch up to the rest of the disk-based backup and continuous data protection markets and offer products worth buying.

Consider implementing near-real-time replication or continuous data protection. These technologies have two important advantages. First, moving data between disks shrinks the backup window. Second, the right products keep tape usage at a reasonable level, as you can choose which data is important enough to go from replica to tape.

Replication from vendors such as XOsoft and DataMirror provides discrete, point-in-time, disk-to-disk backups. The frequency of those backups differs wildly among products--some replicate every few minutes, others every few hours--so limit your choices to the backup products whose replication options are right for you. Continuous data protection, on the other hand, offered by Revivio, StoreAge Network Technologies, XOsoft and others, offers real-time or near-real-time copying of each data change--a serious amount of traffic that can drag down performance if thousands of users are on the network. With continuous data protection products, you must choose between asynchronous and synchronous replication. Asynchronous won't slow your applications, but is slightly less reliable than synchronous. Meanwhile, synchronous replication, poorly implemented, can bring your entire storage infrastructure to its knees as it waits for a response for each copied write. If your setup is designed to copy across the Internet, you'll encounter massive delays. Find out what your vendor has to offer to maximize reliability and performance, but realize that there's a trade-off between the two.