For the largest group of databases and servers, the options are more limited and push into hardware that is much more cutting edge. Quite a few companies are now running databases that reach 100s of GB and a few at the TB level. You obviously need much better capacity than a single DLT will provide.

Tape is still the old standby, even in these environments. However, they will be taking advantage of advanced backkup features in SQL Server and also advanced hardware.

The first thing that can obviously be done is to hook up more than one DLT drive. SQL Server backups can take advantage of this natively and support any number of backup devices. When utilizing multiple backup devices, SQL Server uses a striped backup solution. This means that it writes the data across all devices during the backup process. No single device contains a complete picture of the data, but instead contains multiple sections of a database. When utilizing this capabilty, it is highly recommended that you utilize the description, media name, and name options to help identify the backup. These tapes will need to be kept together in a group, because overwriting any tape will invalidate the entire backup. You also get significant increases in backup speed. Each backup device will get its own thread in the backup process. This means that if you have 1 device, 1 backup thread is running. Two devices equals 2 threads, etc. This means two devices can accomplish your backup in almost half the time it takes to perform a backup to a single device. Uutilizing striped backkups meets the needs of many of these large environments in terms of capacity and time required to complete the backup.

The next step up from multiple tape devices is the highest class of tape hardware that is available. These are devices that support multiple machines. They come in two different varieties: autoloaders and tape libraries. Each one has the capability to manage between several tapes all the way to hundreds of tapes.

The autoloaders do exactly what the name says. These are machines that write to a single tape at a time. The difference is that no human intervention is required to switch tapes. Once a tape has become ful, it is ejected and the autoloader removes it and inserts the next tape in the unit so the process can continue.

Tape libraries are a step upfrom an autoloader. These are designed to handle the higest capacity of tapes. Not only to they offer the automatic load features of an autoloader, but they can also write to multiple tapes at the same time. You will normally find autoloaders and/or tape libraries in the largest environments.

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