8 May 2012

Fixing a hard drive’s firmware is quite straightforward: just locate the corrupted modules in the System Area and fix them. However, what if the drive cannot write to the System Area to fix corrupted modules? There is still a way around this problem: a method called Hot Swap.

Firmware corruption on modern hard drives usually occurs when one or more modules are damaged in the System Area on the disk platters. Fixing this type of problem requires specialized utilities to test and repair corrupted modules. Usually, the repair can be done using PC3000 on the fly, and it doesn't require any extra steps to perform.

Sometimes, however, some modules can’t be fixed. This could be due to the following reasons:

1. There is media damage in the System Area, so heads cannot write in that area.
2. There is some damage to system heads write elements, so heads cannot write at all.
3. Modules containing unique write parameters for the heads (adaptives) are corrupted, so the drive cannot write.
4. The hard drive doesn't give access to System Area if some critical modules are corrupted.

If some modules can’t be fixed, the solution is to use the Hot Swap method to access the drive System Area and try to repair the modules.

A Hot Swap procedure generally follows these steps:

1. Use a matching donor drive, enter the specialized utility, and make sure that the drive is in working condition.
2. Put the donor drive into Standby mode using a special command from within the utility. This command makes the drive spin down the motor without cutting power to the drive.
3. Carefully hot-swap the board by disconnecting it from the good donor drive and connecting it to the bad drive. Even though the drive is not spinning, the board is still alive.
4. Wake up the drive by executing Recalibrate or another ATA command; if the donor drive was compatible enough, the bad patient drive should spin up and become ready.
5. Test the System Area and repair corrupted modules as needed.

So, the idea is essentially to initialize a donor PCB with firmware from the donor drive, then hot-swap the board to the faulty hard drive and repair corrupted modules.

This procedure can usually be applied for cases c) and d). Unfortunately, when there is a hardware problem with heads (b) or media (a), hot swapping won't allow you to repair corrupted modules. For these complex cases, there is a Smart Hot Swap method to use, which we will explain in another post.

Stay tuned.