Overview

Overview of advanced features such as multipath architecture, multiple logical libraries, and multiple control paths.

Multipath architecture

The multipath architecture feature of this tape library allows Open Systems applications to share the robotics of the library. See Library sharing.

The library features storage area network (SAN) ready multipath architecture. This architecture allows homogeneous or heterogeneous Open Systems applications to share the library's robotics without middleware or a dedicated server (host) acting as a library manager. The SAN-ready multipath architecture makes sharing possible by partitioning the library's storage slots and tape drives into logical libraries. Servers can then run separate applications for each logical library. This partitioning capability extends the potential centralization of storage that the SAN enables. Partitioning also provides investment protection if your application does not support the mixing of drive generations and media in the same logical library.

The multipath architecture of this library is designed to provide the capability to share the library robotics. The sharing is accomplished first by partitioning the library into multiple logical libraries (up to the number of drives installed). Then, each logical library is assigned its own separate and distinct drives, storage slots, and control paths. Input/output (I/O) slots are shared on a first-come-first-serve basis. This type of partitioning is designed to allow heterogeneous applications to share the library robotics independent of each other. Cartridges under library control are not shared between logical libraries, nor are they allowed to be moved between logical libraries. An example of heterogeneous sharing is a Microsoft™ Windows™ application that is using the drive and storage slots of one logical library, while a UNIX® application uses the drive and slots of another logical library. See Mixed drives.

Multiple logical libraries

A library can be partitioned into multiple logical libraries to enable simultaneous data backup and restore tasks from different applications. For example, you can create multiple logical libraries so that is processes
  • Commands from Application 1 (about Department A) in Logical Library 1
  • Commands from Application 2 (about Department B) in Logical Library 2
  • Commands from Application 3 (about Department C) using Sequential Mode in Logical Library 3

In this configuration, the tape drives and cartridges of each logical library are dedicated to that library and are not shared among other libraries and applications. Commands that are issued by the applications travel to the library through unique control paths or sequential mode processing by the library. So, the data processing for Department A is confined to the tape drives and cartridges of Logical Library 1. Processing for Department B is confined to the tape drives and cartridges of Logical Library 2, and so forth.

For applications that do not support mixed drive types and media within the same logical library, partitioning the library into multiple logical libraries provides the capability to keep them separate. For example, you can partition the following tape drives and their media into multiple and separate logical libraries:
  • LTO™ 8
  • LTO 7
  • LTO 6

Multiple control paths

With this tape library's multipath architecture, in addition to creating multiple logical libraries, you can configure any logical library to have more than one control path. A control path is a logical path into the library through which the library receives standard SCSI Medium Changer commands to control the library operations.
Note: No SCSI Medium Changer is configured when the logical library is enabled as Sequential Mode

Multiple control paths reduce the possibility of a failure in one control path to cause the entire library to become unavailable. Also, when you configure more control paths, more library-sharing configurations and options are possible. Access to the library is on a first-come, first-served basis. Each control path for a logical library can accept commands while the library is in use by another control path.

Multiple control paths for control path failover

This tape library offers an optional control path failover feature. See Library sharing and Control path failover, Data path failover, and load balancing.

Use of the control path failover feature further reduces the possibility of a failure in one control path to cause the entire library to become unavailable.

The control path failover feature (feature code 1682) enables the host device driver to resend a command to a different control path for the same logical library.