OAM attempts to balance drive use within a given library; however, in a system with multiple libraries, the level of activity can vary greatly among libraries. Activity can be affected by the assignment of Object or Object Backup storage groups to libraries, the frequency of retrieval of objects from optical or tape cartridges, and the availability of scratch cartridges.

If one library has much more activity than the others, the response time for work on that library can be lengthened. You should monitor the number of cartridge mounts in each library by examining the console log.

To balance the work load, reassign Object or Object Backup storage groups to other libraries, and eject and move the cartridges to the corresponding libraries. Also, for an Object storage group that is defined to be resident in multiple libraries, cartridges in the Object storage group can be ejected from the overly active library and entered into another library assigned to the Object storage group.

When determining which volume to use for a write request, OAM attempts to find the volume that is available to the storage group and that has the least amount of free space, but enough space for the object that is to be written. If a new library is added to a configuration and the new library is added to an existing Object or Object Backup storage group definition, it is a good idea to move some of the partially used volumes that belong to the Object or Object Backup storage group instead of populating a new library only with scratch or unused grouped volumes. This will help to distribute the read and write workload across the libraries.