Signal characteristics, Power, Ready LED Out

9.4.6SAS transmitters and receivers

A typical SAS differential copper transmitter and receiver pair is shown in Figure 19. The receiver is AC cou- pling to eliminate ground shift noise.

	TX	.01
	Transmitter	Differential
	Transmitter	Transfer Medium
	100	Transfer Medium
	100
	TY	.01

Figure 19. SAS transmitters and receivers

Receiver 100

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 15 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 16.

Table 16: 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

Cheetah T10 SAS Product Manual, Rev. A

ST3300555SS, ST3146755SS, ST373355SS specifications

The Seagate ST373355SS, ST3146755SS, and ST3300555SS represent a range of high-performance hard drives designed for enterprise applications, particularly in server environments requiring reliability, speed, and high capacity.

The ST373355SS is a 73.5 GB SCSI hard drive operating at 15,000 RPM, which ensures rapid data access and superior performance, making it ideal for transactional applications and data-intensive tasks. With its 4 MB cache, the drive leverages fast read and write speeds, enhancing overall system responsiveness. The SCSI interface, operating at 80 MB/s, allows for high-speed data transfers, making it a suitable choice for demanding environments where quick access to information is critical. Its hot-swappable feature enables maintenance without shutting down the system, maximizing uptime and productivity.

The ST3146755SS, with a capacity of 146.8 GB, builds on the performance of its predecessor while introducing improvements in data handling and reliability. Operating at the same impressive 15,000 RPM, this model also features a 16 MB cache that greatly improves data throughput and access speed. The drive is designed to reduce latency, which is crucial for applications where timing is everything. It is equipped with advanced error recovery features and Seagate’s innovative PowerTrim technology, which improves power efficiency during read and write operations. The ST3146755SS also features a higher mean time between failures (MTBF), underscoring its reliability in high-demand environments.

Lastly, the ST3300555SS offers even greater capacity with 300 GB. This drive maintains the 15,000 RPM rotation speed and benefits from a 16 MB cache, providing a balance of speed and storage capacity. Its advanced SCSI interface supports not just speed but also data integrity, ensuring consistent performance during extensive data transfers. The drive is designed to handle workloads naturally associated with enterprise servers, data warehouses, and video editing applications. Its rugged build supports continuous operation and is tested for high-temperature environments to ensure durability.

In summary, the Seagate ST373355SS, ST3146755SS, and ST3300555SS hard drives are engineered for enterprise environments, combining impressive RPM speeds, significant storage capacities, and advanced technologies to deliver reliability, performance, and efficiency for critical applications. These hard drives represent Seagate's commitment to providing solutions that meet the rigorous demands of modern data environments.

Seagate ST3300555SS Signal characteristics, SAS transmitters and receivers, Power, Ready LED Out

Models: ST3300555SS ST3146755SS ST373355SS