Numbering scheme overview

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The following library elements are numbered:

  • Modules
  • Slots (storage and I/O)
  • Drives

The library controller cards and power supplies are not numbered separately. They are identified according to the module in which they are installed.

Logical Element IDs

Logical Element IDs are the primary method that is used in library interfaces and logs to uniquely identify each library element. They are often called “logical IDs” or just “IDs”. All elements are numbered, starting at 1, from the bottom of the library to the top.

Module numbering can be viewed in the Library Menu of the Navigation Dock in the Management GUI.

Drive numbering can be viewed in the Drive Menu of the Navigation Dock in the Management GUI. Only installed drives are assigned a drive ID

Slot numbering can be viewed in the Cartridge Menu of the Navigation Doc in the Management GUI. The slot numbering system for each module is described in the magazine section. It starts in the front bottom slot of the left magazine and progresses to the rear. It then continues at the bottom rear of the right magazine and progresses to the top front. Slot IDs have the number of the module listed first, then a dot (.) and then the slot ID within the module. For example, 2.5 is the 5th slot in module 2.

Figure 1. Element numbering Example for a 3-module 21U library

Physical Element Numbering

Sometimes an element ID has a different number (often in parentheses) next to it. This number is called a Physical Number, Phy Num, or PNUM. PNUMs are used by the software and are only useful in complex troubleshooting. They are referenced to the base module, so they do not change when modules are added or removed from the library. For example, 2 (4) is the designation for the base module in the library example above. The module ID is 2 and it has a PNUM of 4. Configuring logical libraries does not change the element ID or PNUM, it just assigns the element to a specific logical library.

SCSI Element Addressing

SCSI Element Addressing (defined by industry SCSI standards) assigns identifiers to library elements that are used by software applications. SCSI element addresses appear in logs and library interfaces along with Element IDs and PNUMs. Configuring logical libraries changes the SCSI element addresses.

The Library Element Numbering Details topic in the Troubleshooting Section gives a more detailed description of library numbering along with more examples.