Terminating The Bus; Scsi Connectors And Adapters; Scsi Differential - Lvd; Sas Interface - IBM TS3100 Setup, Operator, And Service Manual

Removal of any jumpers creates a SCSI bus for each drive that is installed in your library for attachment
to multiple servers or to multiple SCSI adapter cards on one server. Each SCSI bus must be terminated.
Multiple SCSI buses might be required for maximum performance, depending on the application and
data compression ratio. Note, however, that library (Medium Changer) control is required on at least one
SCSI bus.
The Medium Changer device is required to be addressed via LUN 1 of the lowest-numbered drive
position of each logical library. The Medium Changer device might be addressed via LUN 1 of other
drives in any logical library.
Any bus that contains a Medium Changer device by way of LUN 1 of a drive is referred to as a control
and data path. Any other bus is referred to as a data path. For information about control paths, see
"Multiple control paths" on page 28.

Terminating the bus

The SCSI bus and all of the wires in the SCSI cable must be properly terminated according to the SCSI
standard.
You can plug an external terminator into one of the SCSI connectors. A terminator must be installed on
the last device on each end of a string of multiple devices. A terminator is included with each SCSI
Ultrium Tape Drive.

SCSI connectors and adapters

The library is supported by a wide variety of servers (hosts), operating systems, and adapters. These
attachments can change throughout the product's lifecycle. To determine the latest supported attachments,
visit the web at http://www.ibm.com/storage/. Or, contact your IBM sales representative.

SCSI differential - LVD

IBM LVD tape devices support a bus length of 25 meters (82 ft.) point-to-point, and 12 meters (39 ft.)
with multi-drop interconnection (daisy-chaining). For each daisy-chained device, the maximum cable
length must be reduced by 0.5 meters (1.6 ft).
Important: A faster bus does not imply that an attached device supports that data rate, but that multiple
devices can operate on the bus at that maximum speed. For a detailed table of SCSI terms and related
specifications, refer to the SCSI Trade Association website at http://www.scsita.org/terms/scsiterms.html.
To ensure best performance, avoid daisy-chaining, if possible.

SAS interface

A drive sled with a SAS (Serial Attached SCSI) interface is linked directly to controllers. SAS is a
performance improvement over traditional SCSI because SAS enables multiple devices (up to 128) of
different sizes and types to be connected simultaneously with thinner and longer cables. Its full-duplex
signal transmission supports up to 6.0 Gb/s. The SFF-8088 SAS connectors on the Ultrium 5 and later
tape drives are compatible with SAS-1 or SAS-2 cables. The SFF-8088 SAS connectors on the Ultrium 3
and Ultrium 4 tape drives are compatible with SAS-1 cables. In addition, SAS drives can be hot-plugged.
SAS drives auto-negotiate speed. No configurable topologies, thus no feature switches are associated with
SAS. The SAS Ultrium 3 and Ultrium 4 half height drive sleds are single ported and are attached only to
one host. The Ultrium 4 and Ultrium 5 full height, and Ultrium 6, Ultrium 7, and Ultrium 8 half height
drives are dual ported, and are attached to a maximum of two hosts. The intention of the second port is
for redundancy for failover rather than sharing. Sharing between these two hosts is limited to
active/passive cluster failover. LAN-free drive sharing is not supported. Ultrium 3 and Ultrium 4 SAS
drive sleds use the SFF-8088 connection at the drive sled end and SFF-8088 or SFF-8470 at the host
adapter end.
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Installation planning