ULTRA2 LVD SCSI HOST ADAPTER

4.2 Attaching Other SCSI Devices to the Adapter’s Bus

You can connect as many as fifteen internal and external SCSI devices to your Ultra2 LVD SCSI Host Adapter. Follow the directions listed in this section. (If you are connecting SCSI devices to multiple Adapters to form a clustered system, refer to Section 4.5.)

4.2.1CONNECTING INTERNAL SCSI DEVICES

If you are connecting internal SCSI devices, make sure to use a SCSI ribbon cable that (a) is not too long (see Section 3.3), (b) has the appropriate characteristics (see Section 3.3), and (c) has enough connectors to accommodate the Adapter and all of your internal peripherals. Figure 4-3 below shows the preterminated Wide (68-pin) internal cable that comes with the Adapter; it has enough connectors for four internal SCSI devices.

Built-in

Terminator

Connect

(Connect remaining

Connect 2nd

Connect 1st

to the

SCSI devices to other

SCSI device

SCSI device

Adapter

intermediate connectors)

here

here

Figure 4-3. The Adapter’s included internal ribbon cable.

This cable is 125 cm (4.1 ft.) long; whether you use it or some other cable, keep in mind that the total length of cable on the Adapter’s SCSI bus, including both internal and external cables, mustn’t exceed 12 m (39.4 ft.) unless you’re attaching one and only one peripheral, in which case you can run as far as 25 m (82 ft.). And this assumes that all of your devices are Ultra2 SCSI LVD compliant; if you are attaching any legacy devices, the maximum total bus length will be much less:

•6 m (19.7 ft.) if the only legacy devices attached to the bus are SCSI-1 or Fast SCSI (SCSI-2) devices.

•3 m (9.8 ft.) if you have four or fewer devices attached to the bus and any of them are Ultra SCSI (SCSI-3) devices.

•1.5 m (4.9 ft.) if you have five or more devices attached to the bus and any of them are Ultra SCSI (SCSI-3) devices.

The cable should have an impedance of at least 120±8 ohms if any Ultra2 SCSI LVD devices are attached; the impedance can be as low as 90±8 ohms only if all attached devices are non-Ultra2-type.

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Black Box SCSI-2 LVD manual Attaching Other Scsi Devices to the Adapter’s Bus, Adapter’s included internal ribbon cable
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SCSI-2 LVD specifications

The Black Box SCSI-2 LVD (Low Voltage Differential) represents a significant advancement in data storage and connectivity technology, particularly in environments requiring high performance and reliability. As a variant of the SCSI (Small Computer System Interface) standard, it is optimized for faster data communication, essential for modern computing needs.

One of the main features of SCSI-2 LVD is its capability to handle increased data transfer speeds compared to its predecessors. It supports a maximum data transfer rate of up to 80 MB/s, which is double that of the original SCSI-2 single-ended signaling. This increase in speed is largely due to the differential signaling that LVD employs, allowing for reduced electromagnetic interference and extended cable lengths while maintaining signal integrity. The technology effectively converts the SCSI bus into a more robust system that can accommodate various devices without compromising performance.

The SCSI-2 LVD standard is backward compatible, meaning that it can interface with older SCSI devices, albeit at reduced speeds. This compatibility is significant for users looking to upgrade their systems without discarding existing hardware. This makes SCSI-2 LVD an attractive choice for enterprise environments where legacy systems are common.

Another key characteristic is the flexible cabling options provided by SCSI-2 LVD. It can support cable lengths of up to 12 meters, which is beneficial for large data center configurations where space between devices can be substantial. This extended range does not typically come at the expense of performance, ensuring that data integrity remains high, even over longer distances.

In terms of technology, LVD employs lower voltage levels, which not only contributes to greater power efficiency but also minimizes heat generation in devices. This is particularly crucial in data centers where temperature management can impact hardware longevity and reliability. The combination of lower voltage use and differential signaling makes SCSI-2 LVD well-suited for high-density environments.

Error correction and handshaking features are also integral to SCSI-2 LVD, enhancing its robustness against data loss during transmission. These characteristics make it a reliable choice for applications requiring consistent and high-speed data access, such as server arrays and high-performance computing tasks.

Overall, Black Box SCSI-2 LVD stands out due to its impressive speed, compatibility, and extensive cabling options, positioning it as a reliable solution for demanding data environments. It effectively bridges the gap between legacy systems and modern technology, ensuring that users can optimize their data handling capabilities without significant disruption.
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