Dell TL2000 SAS Interface, Fibre Channel Interface, Terminating the Bus, Scsi Differential LVD

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 may additionally be addressed via LUN 1 of other drives in any logical library.

Any bus containing a Medium Changer device via 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 “Using Multiple Control Paths” on page 3-2.

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 Differential - LVD

LVD tape devices support a bus length of 25 meters (82 ft.) point-to-point, and 12 meters (39 ft.) using 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 will support 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 Web site at http://www.scsita.org/terms/scsiterms.html. To ensure best performance, if possible, avoid daisy-chaining.

SAS Interface

A drive sled with a SAS (Serial Attached SCSI) interface can be 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 3.0 Gb/s. In addition, SAS drives can be hot-plugged.

SAS drives will auto-negotiate speed. There are no configurable topologies thus no feature switches associated with SAS. The SAS Ultrium 3 and Ultrium 4 Half height drive sleds are single ported and can only be attached to one host. While the Ultrium 4 Full height drive is dual ported and can be 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. Initially, only point-to-point connections are supported.

Fibre Channel Interface

Fibre Channel allows for an active intelligent interconnection scheme, called a Fabric, to connect devices. Everything between the ports on Fibre Channel is called the Fabric. The Fabric is most often a switch or series of switches that takes the responsibility for routing.

The library allows the selection of the following Fibre channel port behaviors:

3-8Dell PowerVault TL2000 Tape Library and TL4000 Tape Library User's Guide