9.4.6SAS transmitters and receivers

A typical SAS differential copper transmitter and receiver pair is shown in Figure 15. The receiver is AC cou- pling to eliminate ground shift noise.

 

TX

Transmitter

Differential

Transfer Medium

100

 

 

TY

Figure 15. SAS transmitters and receivers

.01

.01

RX

Receiver 100

RY

9.4.7Power

The drive receives power (+5 volts and +12 volts) through the SAS device connector.

Three +12 volt pins provide power to the drive, 2 short and 1 long. The current return for the +12 volt power supply is through the common ground pins. The supply current and return current must be distributed as evenly as possible among the pins.

Three +5 volt pins provide power to the drive, 2 short and 1 long. The current return for the +5 volt power sup- ply is through the common ground pins. The supply current and return current must be distributed as evenly as possible among the pins.

Current to the drive through the long power pins may be limited by the system to reduce inrush current to the drive during hot plugging.

9.5Signal characteristics

This section describes the electrical signal characteristics of the drive’s input and output signals. See Table 12 for signal type and signal name information.

9.5.1Ready LED Out

The Ready LED Out signal is driven by the drive as indicated in Table 13.

Table 13: Ready LED Out conditions

Normal command activity

 

LED status

 

 

 

Ready LED Meaning bit mode page 19h

0

 

1

 

 

 

 

Spun down and no activity

Off

 

Off

 

 

 

 

Spun down and activity (command executing)

On

 

On

 

 

 

 

Spun up and no activity

On

 

Off

 

 

 

 

Spun up and activity (command executing)

Off

 

On

 

 

 

 

Spinning up or down

 

Blinks steadily

 

(50% on and 50% off, 0.5 seconds on and off for 0.5 seconds)

 

 

 

Format in progress, each cylinder change

 

Toggles on/off

 

 

 

 

Barracuda ES.2 SAS Product Manual, Rev. E

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Seagate ST31000640SS, ST3750630SS, ST3500620SS Signal characteristics, SAS transmitters and receivers, Power, Ready LED Out
Page 62 Page 64

ST31000640SS, ST3500620SS, ST3750630SS specifications

Seagate has been a leading name in the storage industry for decades, and its range of enterprise-class hard drives showcases advanced technologies and robust performance. The Seagate ST3750630SS, ST3500620SS, and ST31000640SS are three notable models that cater to the demands of data centers and enterprises. Each model is designed with specific features that enhance reliability and efficiency, making them suitable for various applications.

The Seagate ST3750630SS is a 750GB 15K RPM Serial Attached SCSI (SAS) drive. It boasts a high-performance architecture that allows for fast data transfer rates, making it ideal for high-load environments such as transaction processing and video streaming. This drive features an MTBF of 1.6 million hours, ensuring minimal downtime due to failures. It also employs advanced error recovery and data protection mechanisms, including error correction codes (ECC), to maintain data integrity.

Meanwhile, the ST3500620SS offers a capacity of 500GB with a spinning speed of 15K RPM as well. This drive utilizes the SAS interface, providing users with improved bandwidth and connectivity compared to traditional SATA drives. The ST3500620SS is designed with a focus on high availability, featuring a robust design that supports multiple workloads simultaneously. Its quick access times enhance overall system performance, making it a preferred choice for high-performance computing applications.

The ST31000640SS is another enterprise-class offering, delivering 1TB of storage capacity. Like its counterparts, this drive operates at 15K RPM and utilizes the SAS interface, facilitating fast data processing and retrieval. It also incorporates a dual-port design which allows for redundancy and failover capabilities. This feature is critical in enterprise environments where data access and uptime are paramount. The drive's design is optimized for durability and longevity, best suited for environments that require 24/7 operation.

All three Seagate drives feature advanced technologies such as dual-stage actuators and thermal write technology, ensuring improved read and write performance, along with reduced power consumption. Additionally, they are built to endure the rigors of enterprise workloads, including heavy I/O operations and high access demands.

In summary, the Seagate ST3750630SS, ST3500620SS, and ST31000640SS are exemplary models that reflect the company’s commitment to quality and performance in enterprise storage solutions. With their high speeds, reliability, and extensive features, these drives are well-equipped to meet the challenges of modern data-driven environments.
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