Specifications

9 ATTO Technology FibreBridge 4500 Installation and Operation Manual
2.3 Connecting SCSI devices to SCSI ports
ATTO FibreBridge SCSI ports are used to connect SCSI storage devices into the Fibre Channel Storage
Area Network (SAN).
A FibreBridge may have the following types of
SCSI ports:
Ultra 2 (LVD) SCSI 80 MB/sec. max per bus
Single Ended Ultra SCSI 40 MB/sec. max per bus
High Voltage Differential (HVD) Ultra SCSI 40
MB/sec. max per bus
The high voltage differential (HVD) FibreBridge
is compatible only with HVD SCSI devices. An
LVD FibreBridge is downward compatible with
Single Ended Ultra SCSI as well as Fast, Wide, or
Narrow SCSI devices.
Each SCSI port is totally independent from the
any other SCSI port. This means that each bus is
capable of supporting 15 devices and each bus is
capable of 40 or 80 MB/sec. (Ultra or Ultra2).
However, you may use externally provided
software striping to create a RAID 0 group that
includes devices from all SCSI busses to increase
overall performance.
Another advantage of independent SCSI ports is
that each SCSI bus auto-negotiates the
appropriate sync rates with the connected devices.
If slower devices are mixed with faster Ultra2
devices, the bus will communicate at the rate of
the slowest device, thus wasting the performance
capabilities of the faster devices. You should
connect slower devices to one SCSI port and
connect faster devices on another port on your
FibreBridge.
The FibreBridge supports a wide variety of SCSI
storage devices including stand-alone drives,
removable drives, JBODs, RAIDs, tape, CD and
DVD drives, changers, libraries and magneto
optical drives.
To connect SCSI devices to the ATTO
FibreBridge:
1Connect a VHDCI SCSI connector from the
SCSI device to a port on the FibreBridge
4500.
Check the type of cable and cable length limit for
each port. It is important to keep cable lengths as
short as possible to ensure the highest signal
quality and performance. These cable lengths
include the wiring inside the devices.
2 Set the IDs of the SCSI devices connected to
the bridge to a value other than 7. You
should use a sequential ID starting at 0 for
each device. Each SCSI port in the ATTO
FibreBridge has an internal factory setting
ID of 7, typical for a SCSI initiator device.
NOTE The entire SCSI bus will operate at the speed of
the slowest device. If you wish to mix devices of different
SCSI speeds on the bridge, it is best to place them on
separate busses. That is, put the slower devices on
bridge SCSI busses 0 and 1, and the faster devices on
bridge SCSI busses 2 and 3. Each bus is independent so
each can operate at different speeds.
3 Terminate each SCSI bus after the last
device. The bridge is terminated internally.
Device type Cable limit
Ultra SCSI Single Ended (SE) 1.5 meters
Ultra SCSI High Voltage Differential (HVD) 25 meters
Ultra2 SCSI Low Voltage Differential (LVD) 12 meters