Assuming you are using IBM tape drives, see the "IBM Tape Device Drivers Installation and Users Guide". The cut/past below is from the section on Dynamic Load Balancing. This works differently than disk multi-pathing.
================================================= The dynamic load balancing support optimizes resources for tape devices that have physical connections to multiple Host Bus Adapters (HBA) in the same machine. When an application opens a device that has multiple HBA paths configured, the device driver determines which path has the HBA with the lowest usage, and assigns that path to the application. When another application opens a different device with multiple HBA paths, the device driver again determines the path with the lowest HBA usage and assigns that path to the second application. The device driver updates the usage on the HBA assigned to the application when the device is closed. Dynamic load balancing uses all Host Bus Adapters whenever possible and balance the load between them to optimize the resources in the machine. For example, consider a machine with two Host Bus Adapters, HBA1 and HBA2, with multiple tape drives attached. Each tape drive is connected to both HBA1 and HBA2. Initially, there are no tape drives currently in use. When the first application opens a tape drive for use, the device driver assigns the application to use HBA1. When a second application opens a tape drive for use, the device driver assigns the second application to use HBA2. A third application would be assigned to HBA1 and a fourth application would be assigned to HBA2. There would be two applications using HBA1 and two applications using HBA2. If the first application finishes and closes the device, there would now be one application using HBA1 and two applications using HBA2. When the next application opens a tape drive, it would be assigned to HBA1, so again there would be two applications using HBA1 and two applications using HBA2. Likewise, if the second application finishes and closes the device, HBA2 would have one application using it and the next application that opens a tape drive would be assigned to HBA2. The dynamic load balancing support is independent from the automatic failover support. Regardless of the path assigned initially for load balancing, if that path fails, the automatic failover support attempts recovery on the next available path. ----------------------------------------- The information contained in this message is intended only for the personal and confidential use of the recipient(s) named above. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this document in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify us immediately, and delete the original message.
