I've been trying to figure out which Seagate command will turn off Auto-Relocation (also called G-list remapping). According to the DeepSpar imager white paper, turning Auto-relocation/G-list remapping off is one of the reasons why people should buy their product. So far I'm not succeeding in figuring out which Seagate command does this. Does anyone know? (Below is a compilation of information from a few web sites:
http://www.deepspar.com/pdf/DeepSparDis ... paper3.pdf page 8
Disabling Auto-Relocation and SMART Attribute Processing
While the methods outlined in the previous section go a long way to obtaining an image of the data, other problems
remain.
When drive firmware identifies a bad sector, it may remap the sector to a reserved area on the disk that is hidden
from the user (Figure 3). This remapping is recorded in the drive defects table (G-list). Since the bad sector could not
be read, the data residing in the substitute sector in the reserved area is not the original data. It might be null data or
some other data in accordance with the vendor-specific firmware policy, or even previously remapped data in the case
where the G-list was modified due to corruption.
Moreover, system software is unaware of the remapping process. When the drive is asked to retrieve data from a
sector identified as bad, the drive firmware may automatically redirect the request to the alternate sector in the
reserved area, without notifying the system before the error is returned. This redirection occurs despite the fact that
the bad sector is likely still readable and only contains a small number of bytes with errors.
Figure 3: G-List Remapping
This process performed by drive firmware is known as bad sector auto-relocation. This process can and should be
turned off before the imaging process begins. Auto-relocation on a drive with read instability not only obscures
instances when non-original data is being read, it is also time-consuming and increases drive wear, possibly leading to
increased read instability.
Effective imaging software should be able to turn off auto-relocation so that it can identify problem sectors for itself
and take appropriate action, which ensures that the original data is being read.
Unfortunately, the ATA specification does not have a command to turn off auto-relocation. Therefore imaging
software should use vendor-specific ATA commands to do this.
http://www.mjmdatarecovery.co.uk/data-r ... rrors.htmlDepending on the hard disk and how it handles bad sectors, when a hard drive comes across a bad sector, it is recorded in a table stored in the firmware zone of the hard disk drive (typically this table is known as a g-list or a grown defect list) and a spare sector is used to replace the bad one. The drawback here, is that if that bad sector was in the middle of a critical file, then chances are that file will no longer open, will appear corrupt, or if it was a system file, then the computer may not even start. When the number of bad sectors exceed the spare sector pool the drive will eventually fail completely or run very sluggishly.
http://www.grc.com/srrecovery.htmDisable Auto-Relocation
Hard disk drives "heal themselves" by replacing defective sectors with spares. This gives the drive the favorable appearance of being "defect free", which is how the drive's manufacturer wants the drive to always appear. The problem is that the drive does this on its own, without asking or notifying, and in the process vital data is too-easily lost.
When a troubled sector is replaced by a spare,
that troubled sector can never again be accessed!
The FIRST THING SpinRite does when it starts examining and working with a drive is to completely disable the drive's built-in automatic sector relocation. This way the drive can't whisk the sector away the first time it's not easily read, and SpinRite can study the sector to recover its data as much as necessary. (And as you might guess by now, no other utility is even aware of this problem.)