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Head recovery procedure enhancement

IP.com Disclosure Number: IPCOM000014583D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2003-Jun-19

Publishing Venue

IBM

Abstract

Disclosed is device firmware that new method of device head recovery. Current head recovery procedure is passive recovery procedure that means the recovery procedure is performed if error(s) are occurred. It takes much time for recovery. This is main cause of system timeout. New method is active recovery procedure, firmware keeps watching head condition and performs recovery procedure if the condition get worse. Therefore system timeout issue will be reduced. Now HDD supports load/unload function. Some error recovery procedure includes load/unload operation and it takes time, but this kind of recovery steps have more effectiveness than shorter one. Basic idea of this new recovery method is performing this error recovery step during device idle. During recovery procedure, firmware judges next step by checking device condition. New recovery method checks device condition if a device enters idle mode (power save mode), then judges whether effective (but taking time) recovery procedure should be performed or not. This method has 2 merits to reduce time for recovery procedure: One is a device can skip load or unload operation. For example, some error recovery procedure should be performed on a ramp, this means unloaded condition. Normally during read or write operation, heads fly above disks, this means loaded condition. Therefore the heads should be unloaded for this kind of error recovery procedure. But if this step performs during low power idle, this means unloaded condition, the device does NOT need load and unload operation for performing this error recovery step. This is the first merit for reducing recovery time. The other is the device can be reduce command execution time. If a device has some trouble, error recovery procedure will perform anyway, and it leads system timeout issues because recovery procedure takes some time. But on new method, errors are recovered during device idle, and this is nothing to do with command execution time, therefore this new recovery method can be reduced execution time. 1