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Tilt adjusted RPO Command Reordering Scheme Disclosure Number: IPCOM000015812D
Original Publication Date: 2002-Jun-01
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 87K

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The main point of invention

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Tilt adjusted RPO Command Reordering Scheme

The main point of invention

This invention is the RPO re-ordering method of the command queue aiming at the improvement in the performance of HDD (Hard Disc Drive). The feature of this invention is having added head change time to the waiting time which is the parameter of RPO re-ordering of command queue. Waiting time is expected waiting time including the generating probability of Miss-revolution. Only seek time was conventionally used for this. In this invention, such waiting time was added to the head change.

The problem solved by invention

Head change time is influenced of seek distance or ambient temperature.If this is not taken into consideration

1) It is computed shorter than the waiting time with the actual prediction value of waiting time.Miss-revolution is carried out as a result. 2) If it is used in this state, Miss-revolution by head change will happen. Therefore, Miss-revolution will happen more mostly than prediction. Therefore, the expected value of waiting time will be computed for a long time beyond necessity, and, thereby, actual waiting time will also become long. The increase in mean waiting time causes a fall of performance. If the time of a head change is predicted pertinently, Mis-revolution will also be controlled, the expected value of waiting time and actual waiting time will also become short, as a result performance will be improved.

The cylinder is located in a line on all the head concentric circle. Therefore, head change time only rectifies a very small position at a change place. Therefore, compared with seeking, it was quick and time was also almost fixed. Therefore, head change time has been calculated as fixed value of short time as compared with seeking. However, head change time is not fixed in fact. On the design, before changing a head, after changing, it must be in the same position. However, each head becomes not perpendicular if pivot bearing which is the axis of VCM inclines by heat expansion or secular change. This causes a position gap, after changing, before changing a head. However, with a former product, since TPI was low, it did not become a problem. however, if a track pitch high-density-izes like t...