Hitachi 7K320 Specifications - Page 66

7K320 SATA OEM Specification the data into its buffer. The device assumes responsibility to write the data subsequently onto the disk.  While writing data after completed acknowledgment of a write command, soft reset or COMRESET does not affect its operation. But power off terminates writing operation immediately and unwritten data are to be lost.  Flush cache, Soft reset, Standby, Standby Immediate and Sleep are executed after the completion of writing to disk media on enabling write cache function. So the host system can confirm the completion of write cache operation by issuing flush cache command, Soft reset, Standby command, Standby Immediate command or Sleep command, and then, by confirming its completion. 12.13 Reassign Function The reassign Function is used with read commands and write commands. The sectors of data for reassignment are prepared as the spare data sector. The one entry can register 256 consecutive sectors maximally. This reassignment information is registered internally, and the information is available right after completing the reassign function. Also the information is used on the next power on reset. If the number of the spare sector reaches 0 sector, the reassign function will be disabled automatically. The spare tracks for reassignment are located at regular intervals from Cylinder 0. As a result of reassignment, the physical location of logically sequenced sectors will be dispersed. 12.13.1 Auto Reassign Function The sectors that show some errors may be reallocated automatically when specific conditions are met. The spare tracks for reallocation are located at regular intervals from Cylinder 0. The conditions for auto-reallocation are described below. Non recovered write errors When a write operation can not be completed after the Error Recovery Procedure(ERP) is fully carried out, the sector(s) are reallocated to the spare location. An error is reported to the host system only when the write cache is disabled and the auto reallocation fails. If the number of available spare sectors reaches 16 sectors, the write cache function will be disabled automatically. Non recovered read errors When a read operation fails after defined ERP is fully carried out, a hard error is reported to the host system. This location is registered internally as a candidate for the reallocation. When a registered location is specified as a target of a write operation, a sequence of media verification is performed automatically. When the result of this verification meets the criteria, this sector is reallocated. Recovered read errors When a read operation for a sector failed once then recovered at the specific ERP step, this sector of data is reallocated automatically. A media verification sequence may be run prior to the relocation according to the pre-defined conditions. 12.14 48-bit Address Feature Set The 48-bit Address feature set allows devices with capacities up to 281,474,976,710,655 sectors. This allows device capacity up to 144,115,188,075,855,360 bytes. In addition, the number of sectors that may be transferred by a single command are increased by increasing the allowable sector count to 16 bits. Commands unique to the 48-bit Address feature set are: Page 66 of 176