HDD failure of the month – WD20EARX / WD1001FALS

In Blog, Hard Disk Drive Recovery Case Study, Successful recovery by Administrator

Western Digital (WD) HDD firmware failure – ‘Slow Responding Fault’


One of the affected WD HDDs with a firmware failure successfully recovered by CDR – Manchester Data Recovery Services

UPDATE 15/06/2016: The fault described in the case study below can be common in all modern Western Digital hard disk drives. CDR has seen a large number of Western Digital My Passport HDDs with also have the ‘slow responding’ fault.


Including models WD20EARX-xxPASB0 / WD1001FALS-xxY6A0

Unlike last month’s post detailing the motor seizure failure of a particular series of Seagate/Samsung HDDs, this failure in WD disks does not relate to a particular model or series within the Western Digital hard disk drive range. Instead, it affects many modern WD HDDs. The fault relates to a failure of the HDD’s firmware. The firmware is the software/code which provides the functionality of the HDD.

The fault relates to a firmware module titled the ‘Relo-list’. This module combined with the ‘G-List’ (growth defect list) monitors the number of defects on the hard disk drive. The failure of these modules can often be due to a large number of unreadable sectors on the hard disk drives. Sometimes these unreadable sectors can be located within the firmware modules, which then presents an additional problem.

How to recover the data

WD Slow Responding PC3000

Use of PC3000 to resolve the relo-list ‘slow responding’ fault in Western Digital hard disk drives

It is necessary to correctly identify the fault based on an analysis of the service area where the firmware modules are stored. This is conducted using AceLab’s PC3000 Express data recovery tools. If there are unreadable sectors in the service area (SA) it is necessary to reallocate the Relo-list module to another area in the SA, then upload a donor module from a matching HDD and then repair the Relo-list module. Assuming that access to the LBA (data) areas is then possible it is then usually necessary to clone the hard disk drive with suitable disk imaging equipment (Data Extractor or DeepSpar Disk Imager) as it is likely there will be a significant number of bad sectors.

Once this is complete the filesystem is rebuilt and the data extracted for testing. A file listing is then sent to the customer detailing the recovery. Usually CDR – Manchester Data Recovery Services – will make a full recovery of the data in these cases of firmware failure.