Virtual I/O slots
With the Advanced Library Management System (ALMS), virtual I/O slots enhance the import and export capabilities of the library.
When ALMS is enabled in a TS3500 tape library, virtual I/O slots are enabled by default so that the library automatically queues all cartridge moves between the I/O station and the storage slots. This capability makes the process of adding and removing cartridges easier and faster. To disable this feature, refer to Enabling or disabling virtual I/O slots. For information about the default setting for maximum available virtual I/O slots (Max VIO Slots) and how to change that setting, refer to Import/export element addresses with virtual I/O slots enabled.
The TS3500 tape library has I/O stations with I/O slots that allow you to import and export up to 224 cartridges at any time. The I/O slots are also known as import/export elements (IEEs). Virtual I/O slots increase the quantity of available I/O slots by allowing storage slots to appear to the host as I/O slots. These storage slots are also called virtual import/export elements (VIEEs). With virtual I/O slots, the library automatically moves cartridges from the I/O stations to the storage slots, enhancing import and export performance, while also decoupling physical cartridge movement from the application thus increasing operator efficiency.
- In a typical import scenario without virtual I/O slots, a library operator is needed to stand at the physical library and fill the I/O station with cartridges; a system administrator is needed to cause the applications to send commands for moving cartridges out of the I/O station and into library storage slots. After operators fill the I/O station with cartridges, the they must wait for the I/O station to be cleared before they are able to insert more cartridges, which means they must wait on the system administrator to clear the I/O station of each set of inserted cartridges. If the library is enabled with virtual I/O slots, the operator can continuously insert cartridges into the I/O station and the administrator does not need to issue commands to move each new set of inserted cartridges. Instead, the library automatically moves the cartridges and places them into virtual I/O slots until they are ready to be processed later as one composite set of inserted cartridges.
- In a typical export scenario without virtual I/O slots, the system administrator might need to export many cartridges from the library. However, after the I/O station is filled, the administrator must wait for the operator to physically remove cartridges from the entire I/O station before the administrator can issue another export command. This operation can be inconvenient. If the library is enabled with virtual I/O slots, the administrator does not have to wait to issue all export commands (up to 255 export commands can be issued at the same time for each logical library) and the operator can remove cartridges from the I/O stations as soon as the accessor automatically moves them from the storage slots.
With virtual I/O slots enabled, the library has various mechanisms for selecting the best storage slot location for each inserted cartridge, as well as the best accessor and I/O station for each ejected cartridge. These mechanisms vary depending on the configuration of your library.
For ejects with virtual I/O slots enabled and I/O stations in both preferred zones of a dual accessor library, the library selects the accessor and I/O stations that are in the same preferred zone as the physical slot of the cartridge to be ejected, but maintains first in, first out (FIFO) order for each zone. For ejects with virtual I/O slots enabled and I/O stations in only one zone of a dual accessor library, the library selects the accessor in that preferred zone and maintains FIFO order.