4.5 Self-calibration

The forces are compensated by adding the measured value to the specified current value to the power amplifier. This makes the stable servo control.

To compensate torque varying by the cylinder, the disk is divided into 23 areas from the innermost to the outermost circumference and the compensating value is measured at the measuring cylinder on each area at factory calibration. The measured values are stored in the SA cylinder. In the self-calibration, the compensating value is updated using the value in the SA cylinder.

(2) Compensating open loop gain

Torque constant value of the VCM has a dispersion for each drive, and varies depending on the cylinder that the head is positioned. To realize the high speed seek operation, the value that compensates torque constant value change and loop gain change of the whole servo system due to temperature change is measured and stored.

For sensing, the firmware mixes the disturbance signal to the position signal at the state that the head is positioned to any cylinder. The firmware calculates the loop gain from the position signal and stores the compensation value against to the target gain as ratio.

For compensating, the direction current value to the power amplifier is multiplied by the compensation value. By this compensation, loop gain becomes constant value and the stable servo control is realized.

To compensate torque constant value change depending on cylinder, whole cylinders from most inner to most outer cylinder are divided into 16 partitions at calibration in the factory, and the compensation data is measured for representative cylinder of each partition. This measured value is stored in the SA area. The compensation value at self-calibration is calculated using the value in the SA area.

4.5.2Execution timing of self-calibration

Self-calibration is executed when:

•

•

•

The power is turned on.

The disk drive receives the RECALIBRATE command from the host.

The self-calibration execution timechart of the disk drive specifies self- calibration.

The disk drive performs self-calibration according to the timechart based on the time elapsed from power-on. The timechart is shown in Table 4.1. After power- on, self-calibration is performed about every five or ten or fifteen minutes for the first 60 minutes or six RECALIBRATE command executions, and about every 30 minutes after that.

C141-E104-02EN

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Fujitsu MHM215OAT, MHM200AT, MHM2100AT, MHL2300AT manual Execution timing of self-calibration, Self-calibration
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MHM215OAT, MHM200AT, MHL2300AT, MHM2100AT specifications

Fujitsu, a leader in storage technology, has developed a range of hard disk drives designed for reliability and performance, catering to both enterprise and consumer needs. The Fujitsu MHM2100AT, MHL2300AT, MHM200AT, and MHM215OAT models are part of this impressive lineup, showcasing various features and technologies that set them apart.

The MHM2100AT model is known for its 2.5-inch form factor, offering a storage capacity of 100GB. It operates at a speed of 5400 RPM, which balances performance and power efficiency. The drive utilizes ATA-6 interface (Parallel ATA) ensuring compatibility with a wide range of systems. One of its primary features is the advanced cache memory architecture, which allows for quicker access to frequently used data. This enhances overall system performance while preserving energy consumption.

The MHL2300AT provides a step up, with its 300GB of capacity. It also maintains a 5400 RPM speed and is designed for optimal heat dissipation and durability. This model is particularly suited for mobile computing applications due to its lightweight design and low power requirements. The MHL2300AT also integrates a sophisticated error correction code (ECC) technology, enhancing data integrity during storage and retrieval processes.

Moving on to the MHM200AT, this unit provides substantial storage of 200GB, maintaining a similar 5400 RPM speed. What sets the MHM200AT apart is its focus on data security with Built-in Security Features such as disk encryption capabilities. This model is suitable for professionals dealing with sensitive information, ensuring both performance and protection against data breaches.

Lastly, the MHM215OAT, another key model, balances user-friendly design with performance metrics. It offers a generous 150GB capacity and features an enhanced seek time for quick file access. With its emphasis on reliability, the MHM215OAT is often utilized in environments where uptime is critical, such as in commercial servers or high-performance workstations.

In conclusion, Fujitsu's MHM2100AT, MHL2300AT, MHM200AT, and MHM215OAT each possess unique features and technologies that cater to diverse user needs. Their combination of efficient power consumption, enhanced data integrity, and reliability make them compelling choices for businesses and individuals alike. Whether for mobile devices, personal computing, or enterprise applications, these models continue to exemplify Fujitsu's commitment to quality and performance in storage solutions.
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