Tape Device Terminology - IBM eserver i5 Handbook

5486ExtStor.fm
Refer to IBM TotalStorage Tape Selection and Differentiation Guide, SG24-6946
to assist you in finding the best tape product solution for the designated backup
environment. The 2004 edition of this Redbook covers the 3494, 3580, 3581,
3582, 3583, 3584, 3590, 3592, and other tape products.

Tape Device Terminology

To help you understand the meaning of some of the functional characteristics of
each tape device, refer to these descriptions:
Random mode: A mode where the library can retrieve and load cartridges at
random from cartridge inventory based on user demand.
Auto mode: A mode where the library sequentially loads cartridges to save or
retrieve data and automatically advances to the next cartridge after a
cartridge 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 be
shared between systems, but the cartridges can be used only by the tape
device dedicated to them.
Multi-control path architecture: Each drive in the library has a control path
to the SCSI media changer. This allows each tape device in a library access
to the robot arm as though it was the only drive in the library.
Multiple partitions: The tape library can be split into partitions. Each drive
has assigned cartridge slots it can use.
Tape pooling: Tape drives are manage as a set (pool of drives). Tape devices
can be attached to separate controllers, but the system software recognizes
resources with equal capabilities in a common library device. At vary on, all
equal resources are displayed under the common library device description.
This allows Backup Recovery and Media Services (BRMS) to assign jobs for
a specific resource to a pool of tapes that are available under this resource. It
is available on OS/400 V4R5 or later.
Performance: The actual throughput that you may achieve is a function of
many components, such as system processor, disk data rate, data block size,
data compressibility, input/output (I/O) attachments, and the system or
application software used. The numbers stated here are the maximum
throughput attainable by the tape device. The best source of information
about performance is the iSeries Performance Capabilities Reference,
SC41-0607.
IBM Eserver i5 and iSeries System Handbook
422
Draft Document for Review October 18, 2004