Sas Interface; Fibre Channel Interface - Dell PowerVault TL2000 User Manual

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 up to 6.0 Gb/s. The SFF-8088 SAS connectors on the Ultrium 5 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 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. The Ultrium 4
full height and Ultrium 5 drives are 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:
v LN Port: (default setting) - an automatic configuration that tries arbitrated loop
first, then switched fabric
Chapter 3. Installation Planning
3-9