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LBA initialization to match the physical location with other HDDs for sync access

IP.com Disclosure Number: IPCOM000010191D
Original Publication Date: 2002-Nov-01
Included in the Prior Art Database: 2002-Nov-01
Document File: 1 page(s) / 8K

Publishing Venue

IBM

Abstract

There was a spindle sync function to enhance the performance to control multiple HDDs with single interface attachment at CHS accessing era, Cylinder/Head/Sector addressing method. When LBA accessing, Logical Block Address addressing, becomes common for HDD accessing, there is no direct relation for the specific sector between the physical location and LBA. This method enables the physically same sector to be allocated with the same LBA number with other HDDs. This enables the performance improvement when multiple HDDs used in parallel as single HDD.

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LBA initialization to match the physical location with other HDDs for sync access

    Two HDD case is described but more than two HDD solution can be easily obtained from these two HDD case explanation.

There are two solutions.

1) Put the primarily defect map area and alternate cylinder twice than used for single HDD.

      There are alternate cylinder and defect sector areas are mapped as defect during manufacturing test phase. LBA will be assigned sequentially but not to use those addressed area. This makes each HDD LBA address becomes different from others.

When attaching two HDDs to the controller, the controller will start initialization. This sequence is to get both HDD alternate cylinder and primarily defect area information and put together and send back to both HDDs. Then the controller directs both HDD to start re-address LBAs with same algorism. As a result all LBAs will be assigned physically same location with those equivalent two HDDs.

The controller and HDD has spindle sync function and the rotation dimension is exactly same between those two HDDs. The controller accesses the data to two HDDs dividing into two by sectors. Synched access makes performance far much better than just operating independently.

There will be reassigned area assigned when the defect area found during field use. But in general those area are very limited and the performance degradation will be small even assigned to another area as recent HDD has reassigned area very close to the def...