Import/export element addresses with virtual I/O slots enabled

This topic describes import/export element addresses in the TS3500 tape library when virtual I/O slots are enabled.

With ALMS and virtual I/O slots enabled on the TS3500 tape library, each import/export element (IEE) address is no longer associated with a specific physical I/O station slot. Instead, I/O slots are virtualized by dynamically associating element addresses to them as required. The association of IEE addresses is accomplished in a way that is completely transparent to the application software.

By using the IBM® Tape Library Specialist web interface, you can select the number of IEE addresses for a logical library (as reported to the host application software by the SCSI Mode Page X'1D') by changing the Max VIO Slots setting for that logical library up to a value of 255. For each logical library, the default value for the quantity of that logical library's IEE addresses is one of the following, depending on when ALMS and virtual I/O slots are enabled:
  • If you enable ALMS and virtual I/O slots before creating a logical library, the number of virtual I/O slots is 255.
    For example:
    1. ALMS and virtual I/O slots are enabled.
    2. One or more logical libraries are created.

      Virtual I/O slots for each logical library defaults to 255 (the maximum number possible).

  • If you enable ALMS and virtual I/O slots after creating a logical library, the number of virtual I/O slots equals the number of physical I/O slots.
    For example:
    1. One or more logical libraries are created.
    2. ALMS and virtual I/O slots are enabled.
      The virtual I/O slots for each logical library equals the number of physical slots in the convenience I/O station for that logical library's media type. Two examples are presented in the following list:
      1. If the physical library has one 16-slot convenience I/O station and one or more logical libraries are created for the LTO media type, you would have 16 virtual I/O slots per each logical library. This number is equal to the number of physical I/O slots.
      2. If the physical library has two 16-slot LTO convenience I/O stations or two 16-slot 3592 convenience I/O stations, and a logical library is created for each media type, the logical library for LTO would have 32 virtual I/O slots and the logical library for 3592 would also have 32 virtual I/O slots.

When you use virtual import/export element addressing, the IEE address range includes addresses from 769 (X'301') to 1023 (X'3FF'), allowing for a maximum of 255 IEE addresses for each logical library.

Each logical library has a unique virtual IEE address space that is not accessible by other logical libraries. In previous firmware releases, the IEE space was made up of physical I/O station slots that were shared by all logical libraries. If a cartridge was moved to and remained in the I/O station, all logical libraries had one less IEE address with which to process imports and exports. Virtual IEEs, however, allow each logical library to use all 255 elements without impacting other logical libraries. For example, two logical libraries might both have 255 cartridges in virtual IEEs 769 through 1023, but the cartridges are actually located in different physical storage slots. Thus, competition for IEE space between logical libraries is eliminated and the effective quantity of IEEs is enhanced without physical modifications to the library. The automatic queuing of a cartridge's moves between the I/O station and the virtual storage slots makes it appear to the host application that the library contains more physical I/O slots than actually exist. Thus, instead of sharing a maximum of 32 I/O slot addresses in Frame 1, each logical library can have up to 255 I/O slot addresses that are not shared.