NVRAM Data Structure

In Hitachi HDD, configuration information including heads map, adaptive parameters etc, is stored in NVRAM chip. This makes the traditional Hot Swap technique invalid for Hitachi HDD. Today, let’s come to know data structure of NVRAM. The data recovery tool which we used is HD DOCTOR for Hitachi. 

Here, we only discuss NVRAM of laptop HDD. ( In desktop HDD, NVRAM is identical for a same family). The picture below shows you typical data structure of NVRAM.

1: NVRAM version, “A60A”

2: Version checksum, “1E602135″ (High byte backward, low byte forward)

3: FW boot flag. “0×01″, boot from SA-A; “0×00″ from SA-C, factory copy.

4: Head map “00 01 02 00″

5: Adaptive parameters of data area, “14F1″ (High byte backward, low byte forward)

6: Adaptive parameters of data area, “83F8″ (High byte backward, low byte forward).

7: “XGH7Z3DM”, S/N on the label.

Attention: the offset of those strings differs from different drive family.

Bookmark

• June 28, 2009 -- Recover NVRAM Data
• July 31, 2009 -- Head damage of 5416