IBM Tape Solutions for Storage Area Networks and FICON

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Chapter 4. Tape building blocks

Consider the tape storage devices available at the moment, and you soon realize that you

have a great variety of tape systems from which to choose. Tape systems range from

stand-alone tape drives, through tape autoloaders, up to large, scalable tape libraries.

However, not all of those products are suitable for a storage area network (SAN) environment.

This chapter explains the fundamental differences between the various tape storage devices,

demonstrates how you can position them in the SAN environment, and shows how to connect

each tape subsystem to the SAN environment.

Currently, most tape subsystems are Small Computer Systems Interface (SCSI) devices and

are connected to a SAN environment by using a SAN Data Gateway. However, direct fiber

attachment is becoming more common for tape subsystems, usually using a Fibre Channel

Arbitrated Loop (FC-AL) connection.

A SAN can provide extended distance for tape applications such as remote vaulting.

However, it also provides much greater flexibility for sharing. This has two implications. First,

you need to consider the sharing capability of a library when you are deciding what type of

library to use. Second, high levels of sharing can make it highly attractive to consolidate tape

work from many small, unshared libraries to a larger, more capable library.

The newest tape technology that we discuss here is provided by the Linear Tape-Open (LTO)

Ultrium tape family. This family goes from single drives through autoloaders to a sharable,

enterprise tape library with features that match well to a SAN environment. Next we describe

the IBM TotalStorage 3590 family, where the 3494 tape library — also offering high capacity,

scalability, and availability — can be shared between multiple systems, including S/390.

Finally, we look at some libraries that you may already have installed and want to attach to

your SAN as a first step in tape SAN exploitation, including IBM TotalStorage MP and DLT

libraries.

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