6.4 Read-ahead Cache

6.4.3.3 Full hit

In this situation, all read requested data is stored in the data buffer. Transfer of the read requested data is started from the location where hit data is stored. For data that is a target of caching and remains before a full hit, the data is retained when execution of the command is completed. This is done so that a new read-ahead operation is not performed. If the full hit command is received during the read- ahead operation, a transfer of the read requested data starts while the read-ahead operation is in progress.

1)An example is the state shown below where the previous read command is executing sequential reading. First, HAP is set at the location where hit data is stored.

 

HAP end location of the previous read command

HAP

HAP (It is reset to the hit data location for transfers.)

Cache data

Full hit data

Cache data

DAP

DAP end location of the previous read command

2)The read requested data is transferred, and a new read-ahead operation is not performed.

HAP (stop)

Cache data

Full hit data

Cache data

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Fujitsu MHW2040AC, MHW2060AC manual Full hit
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MHW2060AC, MHW2040AC specifications

The Fujitsu MHW2040AC and MHW2060AC are notable hard disk drives (HDDs) that have been widely used in various computing applications, especially in laptops and compact devices. These models are part of Fujitsu's commitment to providing reliable storage solutions that meet the demands of modern computing.

The MHW2040AC offers a storage capacity of 40 GB, while the MHW2060AC provides a slightly larger capacity at 60 GB. This range of storage makes both models suitable for users looking for dependable space for documents, multimedia files, and software applications. Both drives utilize a 2.5-inch form factor, ideal for mobile computing, as they are lightweight and designed to fit into space-constrained environments.

In terms of performance, both drives operate at a spindle speed of 5400 RPM. This speed strikes a balance between power consumption and performance, making these drives an efficient choice for everyday tasks, such as web browsing and office applications. The drives are equipped with an interface of Ultra ATA/133, which enables faster data transfer rates compared to older models, thereby enhancing overall system responsiveness.

The MHW2040AC and MHW2060AC also incorporate several advanced technologies to bolster their performance and reliability. One such feature is the use of a fluid dynamic bearing (FDB) for the spindle motor, which minimizes noise and vibration, thus improving the overall user experience. Additionally, both drives come with error correction technology that helps maintain data integrity by detecting and correcting errors during read and write operations.

Moreover, these HDDs feature a shock sensor that can detect sudden movements, allowing the drive to park its heads to prevent data loss and hardware damage. This is particularly beneficial in mobile environments where the risks of impact are higher.

Both the MHW2040AC and MHW2060AC are designed with energy-saving features, making them an environmentally responsible choice for energy-conscious consumers. Their low power consumption not only contributes to a reduced carbon footprint but also extends battery life for portable devices.

In summary, the Fujitsu MHW2040AC and MHW2060AC are reliable, efficient, and user-friendly hard disk drives that combine moderate capacities with advanced features designed to enhance performance, ensure data integrity, and extend device longevity. These drives are well-suited for a range of applications, making them a solid choice for users seeking dependable storage solutions.
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