First let’s take a look at the NVRAM (Non-Volatile Random Access Memory) used on HITACHI HDD, NVRAM is one member of NVM※（see introduction at the end）family, it can process data accessing randomly and keep data even when power is off, but its price is comparatively more expensive than the former ROM.
NVRAM of HITACHI HDD saves important data such as number of HEADs; beginning position of SA, ROM overlay module checkout and platter adaptive parameter.
At present, HITACHI is the first manufacturer to use NVRAM as the media for saving key information.
The following are two typical HITACHI PCBA Layouts; the mark shows the NVRAM position.
In the former HDD products, the important information such as number of HEAD, media adaptive and so on were saved in the ROM chip or the SA on platter. HITACHI first uses NVRAM as the storage media for its key parameters and adopts one very important feature: Random Beginning Position of SA. Each HDD takes a random address as its SA (Serve Area) beginning position (basically we can say in this new tech every HDD has a unique firmware beginning position address). This unique “Random Beginning Position of SA” for each HDD is to be saved in the NVRAM of itself, which means each HDD can work with its original NVRAM only, just like one key opens one lock only; Once the data in the NVRAM is broken or being lost, there will be no operating system or software tool which can detect the HDD, not to speak of working on the SA of the HDD. Therefore, The HDD repair or data recovery becomes mission impossible, even the former universal ways like “HOT SWAP PCB” become useless in such case (the information stored in each NVRAM is unique), we can do nothing about it, the HDD is dead, also your invaluable data. This remains until the “HD Doctor for IBM/Hitachi” of SalvationDATA becomes available.
At present market, we can’t find a data recovery product that can solve this problem effectively. Famous data recovery companies around the world like SALVATIONDATA, ACE etc. are all doing researches on this new technology, and we noticed that SalvationDATA has brought forward an effective solution towards data recovery and HDD repair from IBM/Hitachi HDD which has had the data stored in its NVRAM damaged –HD Doctor for IBM/Hitachi, which will be released by January 2008.
The following is a snap of HD Doctor for IBM/HITACHI:
HD Doctor for IBM/HITACHI can re-configure the hard drive’s NVRAM data according to its properties such as data structure, storage structure and so on, and this will recover the original corresponding NVRAM data. By this way, NVRAM data will be recovered and the HDD is revived.
※ Brief Introductions on NVM
In computer industry, there are three kinds of semiconductor memorizer mostly used.
EEPROM（Electrically Erasable Programmable Read Only Memory）used to save BIOS information. Data can be kept after power off, in recent years, the flash RAM used to save BIOS information is also one kind of EEPROM.
The DRAM（Dynamic Random Access Memory）is used to save temporary data, the data can be kept only by being kept refreshing. The data stored in the chip will be gone when power off.
The SRAM（Static Random Access Memory）is used to save the common instruction and data of the CPU. The data can be kept without being refreshed, but the data stored in the chip will be gone when power off.
Usually, we call the semiconductor memorizer that can keep data after power off “NVM” (Non-Volatile Memory), and Memorizer like DRAM, SRAM is called VRAM.
As the semiconductor memorizer used in HITACHI HDD can access data randomly, it is called NVRAM (Non-Volatile Random Access Memory).
This article is provided by one of SalvationDATA engineers.