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Appendix C. Migrating from the IBM SAN Data Gateway to

fibre-channel attachment

This chapter describes how to migrate a Storage Area Network (SAN) Data

Gateway to a fibre-channel attachment. You must use a bridge or the SAN Data

Gateway to connect between the fibre-channel interface and the SCSI, SSA, or

other interfaces.

Overview of the IBM SAN Data Gateway

The SAN Data Gateway is a protocol converter between fibre channel interfaces

and SCSI interfaces. It supports the following tape drives:

v IBM MP3570

v IBM Magstar 3590

It also supports the following tape libraries:

v IBM Magstar MP3575

v IBM Magstar 3494

v IBM 3502 DLT

The SAN Data Gateway also supports disk subsystems on Intel-based host

systems that runs Windows NT and UNIX-based machines. For the latest list of

operating systems and storage products that IBM supports, visit the followingIBM

SAN Data Gateway Web site:

www.ibm.com/storage/SANGateway/

The SAN Data Gateway is a fully scalable product with up to three fibre-channel

and four ultra-SCSI differential interfaces for disk attachment and tape storage

attachment. Each fibre-channel interface supports dual or single shortwave ports

and single longwave ports. The following is a list of details about the interfaces on a

SAN Data Gateway.

v Fibre-channel

– Supports both loop (private and public) and point-to-point topologies

– Supports distances between the node or switch up to 500 m (50-micron) for

shortwave and 10 km for long-wave

v SCSI

– Has automatic speed negotiation capability for wide or narrow bus widths and

standard, fast, or ultra speeds

– Supports up to 15 target IDs and up to 32 LUNs per ID (subject to an overall

total of 255 devices)

– Supports cable lengths up to 25 m

Note: Although the SAN Data Gateway has a limitation of 255 LUNs, you must

consider the limitations of the operating system, adapter, and storage

subsystem. Whichever is the lowest dictates the maximum number of LUNs

that you can use. Table 27 shows an example of a configuration.

Table 27. LUN limitations for various components

System component LUN limit

Windows NT 4.0 with SP3 120 (15 target IDs times 8 LUNs)