If you have a large amount of data to backup, it can severely impact the performance of your application. Often, backing up to tape drives eats up precious CPU cycles and I/O bandwidth for several hours, when it's really needed to service the application. One way to alleviate this problem is to back up your data over a separate backup network to a machine with a high-speed disk array. You create a backup network by adding a second network card to your application server, then connecting it to a backup server containing the high-speed disk array (see Figure A).

Figure A Expand Your Options

On the backup network, use a protocol with a low overhead, such as NETBEUI or IPX/SPX, for faster transfers. This way you can backup your data over the backup network to the backup server in a fraction of the time it would take to back up directly to tape. This frees your application server to process more application requests. Once you've backed up the data to the backup server, it can go through the slow process of being backed up to tape, without impacting your application server.

There are several benefits to this configuration. First, you can avoid the cost of adding additional hardware to your application server, or dividing your data among several application servers simply to improve backup speeds. Because disk space and network cards are cheap, compared with the cost of additional servers and their associated software, you'll make up for the investment in the backup network, server, and its disk array quickly. Second, you might be able to back up several application servers to the same backup server, avoiding the cost of a tape drive for each application server. You also reduce your management costs for the backup solution, because there are fewer servers to manage, and the backups are now completely centralized. Finally, tape is one of the cheapest backup media per MB, so you will save money on media as well.