Hotswap is the capability to replace a failed part with a spare without having to shut down the system. Hot-Swap is universal for testing and attempts of data recovery from various drives. It is used when service data is damaged and there is no way to check it using built-in means of the drive, for example, because it hangs. There are certain limitations for HOT-SWAP use with any drive. They exist for Western Digital HDD as well:

1.  WD HDDs are sensitive to firmware version. HOT-SWAP is impossible if the target and donor HDD use incompatible versions.
2.  WD HDDs are sensitive to head map contents. HOT-SWAP is impossible if the target and donor HDD use different
head maps.
3.  Data recovery from a WD HDD requires that the target and donor drives use an identical translator, otherwise
complete data restoration will be impossible.

First two conditions can be fulfilled by selection of an appropriate donor drive. Here they are: the donor drive must be a similar model of the same family (the MDL line on HDA case must match), it must use a compatible firmware version and the same head map (it can be verified by reading ROM in Kernel mode). The PCB of the target drive must function normally on the donor HDA.

The third condition cannot be fulfilled by plain selection as there are no two drives with the same P-List tables and, consequently, with identically translators. Therefore, if you need to recover data using HOT-SWAP, you should perform two steps:

1.  Based on the first two conditions, select a donor HDD and perform the first HOT-SWAP during which you should test the firmware modules. In particular, you must verify the integrity of the translator modules ID=20h, 25h or P-
List table, ID=43h. Then these translator modules must be copied to the donor drive (remember to preserve a backup copy of the original donor modules). If the translator modules are corrupted, overwrite the P-List module and Regenerate translator using P-List.

2.  Use the donor thus prepared to perform the second HOT-SWAP after which you can attempt recovery of user data
with the help of some professional data recovery tools.

If you are interested in more data recovery tips, you can continue digging more from this online data recovery book.