3)If the data transfer rate of the INIT (SCSI bus) is lower than the data transfer rate of the disk drive, since the data pre-fetch of data that are to be written to that data block is not completed, it may not be possible to write the data continuously to the disk (data underrun). In this case, the IDD waits one disk revolution while continuing to pre-fetch data from the INIT, then repositions the block that caused the data underrun and continues the writing of data to the disk.

4)After disconnect processing, if all the blocks of data specified in the command have not yet been transferred from the INIT, as writing of data to the disk media progresses, at the point when the empty space in the data buffer reaches the amount specified in the buffer empty ratio in the MODE SELECT parameter, the IDD performs reconnection processing and begins transferring the succeeding data (data pre-fetch).

Writing of data to the disk media is performed in parallel and data transfer with the INIT continues until the empty space in the data buffer is full or until transfer of all the data specified in the command is completed. From then on, disconnection, reconnection and data transfer are repeated until transfer of all the blocks of data specified in the command is completed.

5)When writing of all the specified data is completed, the IDD reports the status and terminates the command.

Notes:

1.If the amount of transfer data specified in a command is smaller than the capacity of the cache segment, all the data necessary for execution of the command are pre- fetched in a batch in the processing in 1) above, so the value specified in the buffer empty ratio has not meaning.

2.If the amount of data processed with a single command exceeds the capacity of one cache segment, in order to avoid frequent repetition of disconnect and reconnect processing during command execution, and in order to escape the occurrence of data underrun, it is necessary to set the buffer empty ratio (see Section 2.1.2) of the MODE SELECT parameter so the difference in the data transfer rates between the INIT (SCSI bus) and the disk drive is maintained in a good balance.

Figure 2.3 shows an example of the data buffer operating state during a write operation. Details are explained in section 2.1.2.

Sector

Disk

Amount of Data in the Buffer

SCSI

DATA OUT

STATUS

Bus

 

 

COMMAND

Disconnection

Reconnection

Figure 2.3 Example of data buffer operation during write

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Fujitsu MAN3184, MAN3367, MAN3735 specifications Example of data buffer operation during write
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MAN3735, MAN3184, MAN3367, MAN3735 SERIES DISK DRIVES, MAN3367, MAN3184 specifications

Fujitsu's MAN3184, MAN3367, and MAN3735 series disk drives represent a significant advancement in storage technology, catering to the needs of businesses seeking reliability, performance, and high capacity. These drives are designed for enterprise environments, providing exceptional data integrity and speed essential for effective data management.

The MAN3184 series is renowned for its high rotational speed of 10,000 RPM, which significantly enhances data access times. With a capacity of up to 18.4 GB, these drives are suitable for applications requiring quick read and write operations. The series employs an improved read/write head technology, which reduces latency and increases overall performance. This technology is complemented by advanced error correction mechanisms, ensuring the reliability necessary for critical data applications.

Transitioning to the MAN3367 series, these drives offer increased storage capacity and improved performance metrics. With capacities reaching up to 36.7 GB, they cater to growing data demands in modern enterprises. They also feature a 10,000 RPM spindle speed, ensuring that the drives can handle intensive workloads with ease. The MAN3367 drives include SCSI interface support, making them versatile and easy to integrate into various systems. The inclusion of intelligent caching algorithms allows for faster data retrieval, while built-in thermal management features ensure optimal performance, even under heavy usage.

The MAN3735 series takes performance up another notch, boasting higher capacities of up to 73.5 GB. These drives are particularly suited for environments that require high reliability and availability. The series utilizes a state-of-the-art SCSI Ultra160 interface, which maximizes data transfer rates, ultimately enhancing overall system efficiency. Additionally, the MAN3735 series employs advanced data protection technologies, including power loss protection and predictive failure analysis, which proactively minimizes potential downtime.

All these series of Fujitsu disk drives are built with a focus on durability and sustained performance. They are designed to operate seamlessly in high-demand environments, ensuring that organizations can rely on them for critical applications. Their compact design and energy-efficient operation make them an ideal choice for modern data centers looking to optimize space and reduce power consumption.

In summary, Fujitsu's MAN3184, MAN3367, and MAN3735 series disk drives deliver a blend of high capacity, performance, and reliability. These drives incorporate advanced technologies that address the evolving needs of enterprise storage solutions, making them a valuable asset for any organization aiming to enhance their data management capabilities.
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