Using Stackers Effectively
Tape stackers are a method of loading multiple tapes into a single tape drive. Only one tape can be accessed at a time, but the stacker will automatically dismount the current tape when it has finished with it and load the next tape. The prices and abilities of these devices vary, but they all have one thing in common: the ability to perform unattended backup. This means that you can back up data up to the full capacity of the stacker before having to involve an operator. This is highly desirable given the number of tapes likely to be involved in a backup, and the consequent risk of error or delay. Some of these devices have limited intelligence and can be controlled programatically. Typically they will allow any given tape to be mounted as required.
This can help, for example, if a restore is required from a recent backup that is still in the stacker. It can also be used to control which tape files are copied to. Some stackers will automatically label the tapes, and can use bar coding to ensure that they have the correct tape loaded. You should check for these sorts of features and compare their value versus the cost of the stacker unit.