The Ready LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the proper +3.3 volt supply through an appropriate current limiting resistor. The LED and the current limiting resis- tor are external to the drive. See Table 17 for the output characteristics of the LED drive signals.

Table 17:

LED drive signal

 

 

 

 

 

State

 

Test condition

Output voltage

 

 

 

 

LED off, high

 

0 V ≤VOH ≤3.6 V

-100 µA < IOH < 100 µA

LED on, low

 

IOL = 15 mA

0 ≤VOL ≤0.225 V

12.5.2Differential signals

The drive SAS differential signals comply with the intra-enclosure (internal connector) requirements of the SAS standard.

Table 18 defines the general interface characteristics.

Table 18: General interface characteristics

Characteristic

Units

1.5Gb/s

3.0Gb/s

6.0Gb/s

 

 

 

 

 

Bit rate (nominal)

Mbaud

1,500

3,000

6,000

 

 

 

 

 

Unit interval (UI)(nominal)

ps

666.6

333.3

166.6

 

 

 

 

 

Impedance (nominal, differential )

ohm

100

100

100

 

 

 

 

 

Transmitter transients, maximum

V

± 1.2

± 1.2

± 1.2

 

 

 

 

 

Receiver transients, maximum

V

± 1.2

± 1.2

± 1.2

 

 

 

 

 

12.6SAS-2 Specification Compliance

Seagate SAS-2 drives are entirely compatible with the latest SAS-2 Specification (T10/1760-D) Revision 16.

The most important characteristic of the SAS-2 drive at 6Gb/s is that the receiver is capable of adapting the equalizer to optimize the receive margins. The SAS-2 drive has two types of equalizers:

1.A Decision Feedback Equalizer (DFE) which utilizes the standard SAS-2 training pattern transmitted dur- ing the SNW-3 training gap. The DFE circuit can derive an optimal equalization characteristic to compen- sate for many of the receive losses in the system.

2.A Feed Forward Equalizer (FFE) optimized to provide balanced receive margins over a range of channels bounded by the best and worst case channels as defined by the relevant ANSI standard.

12.7Additional information

Please contact your Seagate representative for SAS electrical details, if required.

For more information about the Phy, Link, Transport, and Applications layers of the SAS interface, refer to the Seagate SAS Interface Manual, part number 100293071.

For more information about the SCSI commands used by Seagate SAS drives, refer to the Seagate SCSI Commands Reference Manual, part number 100293068.

Constellation ES Series SAS Product Manual, Rev. F

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Seagate ST4000NM0033 manual SAS-2 Specification Compliance, Additional information, LED drive signal, Differential signals
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ST4000NM0053, ST4000NM0023, ST32000444SSIM, ST32000646NS, ST3000NM0063 specifications

Seagate is a prominent name in the storage industry, renowned for its high-performance hard disk drives (HDDs). Among its popular enterprise offerings are models like the ST2000NM0043, ST32000645NS, ST3000NM0043, ST2000NM0033, and ST2000NM0023, which cater to various data center and server needs.

The Seagate ST2000NM0043 is a 2TB 7200 RPM SATA drive designed for high availability and performance in enterprise environments. It features a 128MB cache, ensuring efficient data transfer speeds and quick access to frequently used data. This model boasts a mean time between failures (MTBF) of 1.4 million hours, emphasizing its reliability for continuous operation in demanding applications.

The ST32000645NS, offering 2TB of storage and a 7200 RPM spindle speed, is ideal for environments where large amounts of data need to be stored and accessed quickly. It supports SAS interfaces, providing enhanced data integrity and improved system performance. With its aggressive power management features, this model strikes a balance between performance and energy efficiency, making it suitable for both traditional data centers and cloud applications.

The ST3000NM0043 stands out with a capacity of 3TB, further addressing the growing need for more substantial storage solutions. Like its counterparts, it operates at 7200 RPM and is equipped with advanced caching mechanisms that help enhance overall performance. Its high durability and enterprise-grade features make it a preferred choice for storage-intensive applications.

The ST2000NM0033 focuses on delivering storage solutions for environments needing both capacity and reliability. With its 2TB capacity and 7200 RPM rotation speed, it provides an effective solution for businesses looking to balance workload and storage needs without compromising performance. This model also features Seagate's advanced technology that optimizes workflow and minimizes latency.

Lastly, the ST2000NM0023 mirrors many of the features found in its siblings, offering a 2TB capacity and optimized for high reliability and performance. With Seagate's commitment to innovating in the HDD space, features such as self-monitoring, analysis, and reporting technology (SMART) help maintain the drive's health and prevent potential failures.

In conclusion, Seagate's range of HDDs, exemplified by the ST2000NM0043, ST32000645NS, ST3000NM0043, ST2000NM0033, and ST2000NM0023, reflects a dedication to providing robust, high-capacity storage solutions. Their advanced technologies, reliability ratings, and performance features make them ideal choices for enterprise environments demanding efficiency and durability.
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