Data Buffer Management

2.2.3Look-Ahead operation, Look-Ahead volume

1)Excluding the conditions in 3) and 4) for the amount of data specified as the minimum pre-fetch volume, data are read for look-ahead irrespective of track boundaries or cylinder boundaries. Commands which are already in the queue or commands which are newly received while a look- ahead operation is in progress, are executed after the look-ahead operation is completed. However, if the new command is a READ or READ EXTENDED command, and it is a command in which the first specified logical data block is a sequential access data block, the command is executed without the look-ahead operation being halted. When a newly received command is a command which is not the object of caching, that command is executed immediately in parallel with a look-ahead operation.

Also, in the case of a command which disables all data which are objects of caching (see Section 2.2.1 (3)), the look-ahead operation is halted and that command is executed immediately.

2)When commands exist in the queue, the look-ahead operation is halted at the point when reading of the specified amount of data at the minimum pre-fetch volume is completed, then execution of the new command starts. When there are no commands that need to be newly executed, the data look-ahead operation is continued, even after the volume of data specified as the minimum amount of pre-fetch data have been read, until one of the following conditions, 1), 3) or 4), occurs.

•When "1" is specified in the DISC bit, if look-ahead of data equal in volume to a cache segment is completed.

•When "0" is specified in the DISC bit, if look-ahead of all the data is completed up to the track boundary or the cylinder boundary.

The IDD does not support this function.

3)During a data look-ahead operation, when any error occurs, the data look-ahead operation is terminated at that point (retry is not executed).

4)When a RESET condition occurs on the SCSI bus, or when any INIT issues a TARGET RESET message, the look-ahead operation is terminated at that point and all the look-ahead data stored in the data buffer are invalidated.

5)During a look-ahead operation, if "sector slip processing" is applied, or defective sectors exist in the same cylinder to which "alternate processing" is applicable, the look-ahead operation is continued without interruption.

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Fujitsu MAP3367, MAP3147, MAS3735, MAP3735, MAS3367 specifications Look-Ahead operation, Look-Ahead volume
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MAP3735, MAP3147, MAS3367, MAP3367, MAS3735 specifications

Fujitsu, a renowned leader in technology and innovation, has developed a variety of reliable hard disk drives (HDDs) that cater to a wide range of data storage needs. Among these, the MAS3735, MAP3367, MAS3367, MAP3147, and MAP3735 series stand out for their advanced features and exceptional performance.

The MAS3735 is a high-capacity enterprise-class drive that boasts a storage capacity of up to 300 GB. Its 10,000 RPM spindle speed ensures rapid data retrieval and efficient performance, making it ideal for data-intensive applications. It utilizes a Serial Attach SCSI (SAS) interface, which allows for improved data transfer rates and increased reliability compared to traditional SATA drives. The drive is designed with advanced technologies such as error recovery and data integrity features, ensuring the safety and security of critical data.

Similarly, the MAP3367 and MAS3367 models are geared towards both enterprise and mid-range server environments, providing a storage capacity of up to 300 GB as well. These drives also operate at a spindle speed of 15,000 RPM, offering swift access times that enhance overall system performance. The MAP3367 employs the Ultra 320 SCSI interface, allowing for significant bandwidth and ensuring data is transmitted efficiently.

On the other hand, both MAP3147 and MAP3735 models provide versatile solutions for various applications, supporting capacities from 36 GB to 147 GB. The MAP3147, with its 10,000 RPM speed, is optimized for workloads requiring quick access and high throughput, making it suitable for transactional systems and enterprise applications. The MAP3735, while offering comparable capacity, emphasizes exceptional reliability and durability, which is crucial for environments that involve heavy data loads.

All these Fujitsu HDDs are characterized by their robust construction, reliability, and efficiency. They are built to withstand heavy workloads and are equipped with features like advanced thermal management and acoustic noise reduction, ensuring they operate effectively in data center environments.

In conclusion, Fujitsu's MAS3735, MAP3367, MAS3367, MAP3147, and MAP3735 series HDDs are designed for high performance and reliability, catering to both enterprise and mid-range environments. Their advanced features make them a strong choice for businesses looking to enhance their storage solutions while maintaining data integrity and system performance.
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