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Considerations when configuring multipath tape access

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You can configure two paths from the storage system to access the tape drives in a tape library. If one path fails, the storage system can use the other paths to access the tape drives without having to immediately repair the failed path. This ensures that tape operations can be restarted.

You must consider the following when configuring multipath tape access from your storage system:

  • In tape libraries that support LUN mapping, for multipath access to a LUN group, LUN mapping must be symmetrical on each path.

    Tape drives and media changers are assigned to LUN groups (set of LUNs that share the same initiator path set) in a tape library. All tape drives of a LUN group must be available for backup and restore operations on all multiple paths.

  • A maximum of two paths can be configured from the storage system to access the tape drives in a tape library.

  • Multipath tape access supports load balancing. Load balancing is disabled by default.

In the following example, the storage system accesses LUN group 0 through two initiator paths: 0b and 0d. In both these paths, the LUN group has the same LUN number, 0, and LUN count, 5. The storage system accesses LUN group 1 through only one initiator path, 3d.

STSW-3070-2_cluster::> storage tape library config show

Node                    LUN Group   LUN Count  Library Name  Library Target Port  Initiator
----------------------- ----------- ---------- ------------- -------------------- -----
STSW-3070-2_cluster-01        0      5         IBM 3573-TL_1  510a09800000412d     0b
                                                                                  	0d
                              1      2         IBM 3573-TL_2  50050763124b4d6f     3d

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For more information, see the man pages.