5486ExtStor.fm Draft Document for Review October 18, 2004422 IBM Eserver i5 and iSeries System HandbookRefer to IBM TotalStorage Tape Selection and Differentiation Guide, SG24-6946to assist you in finding the best tape product solution for the designated backupenvironment. The 2004 edition of this Redbook covers the 3494, 3580, 3581,3582, 3583, 3584, 3590, 3592, and other tape products.Tape Device TerminologyTo help you understand the meaning of some of the functional characteristics ofeach tape device, refer to these descriptions: Random mode: A mode where the library can retrieve and load cartridges atrandom from cartridge inventory based on user demand. Auto mode: A mode where the library sequentially loads cartridges to save orretrieve data and automatically advances to the next cartridge after acartridge is filled or restored sequentially. Base mode: All drives see all tapes. Must be attached to one system. Split mode: The tape device is split into two groups. The library can beshared between systems, but the cartridges can be used only by the tapedevice dedicated to them. Multi-control path architecture: Each drive in the library has a control pathto the SCSI media changer. This allows each tape device in a library accessto the robot arm as though it was the only drive in the library. Multiple partitions: The tape library can be split into partitions. Each drivehas assigned cartridge slots it can use. Tape pooling: Tape drives are manage as a set (pool of drives). Tape devicescan be attached to separate controllers, but the system software recognizesresources with equal capabilities in a common library device. At vary on, allequal resources are displayed under the common library device description.This allows Backup Recovery and Media Services (BRMS) to assign jobs fora specific resource to a pool of tapes that are available under this resource. Itis available on OS/400 V4R5 or later. Performance: The actual throughput that you may achieve is a function ofmany components, such as system processor, disk data rate, data block size,data compressibility, input/output (I/O) attachments, and the system orapplication software used. The numbers stated here are the maximumthroughput attainable by the tape device. The best source of informationabout performance is the iSeries Performance Capabilities Reference,SC41-0607.
