Hitachi hard drive firmware 數據恢復細讀

Firmware copy: Copy 0(SA-A), Copy 1(SA-B) and Factory copy(SA-C). Copy 1 is a copy of Copy 0, but not all modules are present in Copy 1. Factory copy locates on different area from Copy 0 and Copy 1 within the service area. There is a flag recorded on NVRAM, which decides which one is boot at power-up.

For drive with more two heads or more, Copy 0 and factory copy locate on primary head while copy 1 locates on secondary head. While for drive with one head only, the three copies locate on the same head.
固件兼容性: there is a version marker recorded in modules like RESF/RAM0/OVR1 etc, which can be used to identify compatible firmware modules.

Hitachi hard drive key firmware modules（日立硬盤固件主要模塊）

USAG/RESF 模塊: Modules table, indicate location of listed module in service area
RSVD 模塊: not listed in modules table; it marks the beginning of service area
Critical 模塊: listed in modules table, critical for drive operation.
Auxiliary 模塊: not listed in modules table, in charge of auxiliary drive operation, e.g., selftest.