Data recovery from the Seagate storage disc. The Unable Load Overlay 01|000 error recovery

I received an order from a far Siberian city of Novosibirsk. The Seagate 7200.10 ST3500630AS Storage disc is not defined by BIOS, data recovery is needed. The client addressed the Nata company, the HDD was accepted for diagnostics but they did not manage to recover data because of spare parts absence.

Broken-down HDD from Novosibirsk
Broken-down HDD from Novosibirsk

During our communication over ICQ I asked the client to scan the upper cover label to clear out what spare disc was needed for repair. It turned out that there were two spare discs at my data recovery shop. The HDD was delivered by UPS, and I diagnosed it. At power on the engine was accelerated with characteristic extraneous noise which testified about so-called notching i.e. physical damages of plates surface. It is very uneasy to recover data from such a disc. More detailed estimation of recovery possibility demands opening the HDD hermetical area and checking condition of internal air recirculation filter, writing heads mr-elements and HDD platters surface. There are three bilateral disks and 6 heads inside ST3500630AS. The surface under the top head was not damaged, and the filter was more or less clean.

The internal air recirculation filter
The internal air recirculation filter

The heads condition analysis under the microscope showed that four of them had been damage physically. Accordingly, at least four of six plates surfaces had radial scratches. I decided to dismantle the entire discs platters for visual estimation of physical damages on the hidden surfaces.

It was quite clear that the platters block dismantle would turn into a serious centering problem. Three plates on an axis could be centered properly only at the factory. But there was nothing to do as installing of serviceable heads complete set without knowing where damages had been located meant assured HDD breakdown.

Dismantling showed expected failure as there were radial scratches on four surfaces in the parking zone.

A radial scratch
A radial scratch

The second radial scratch
The second radial scratch

The third radial scratch
The third radial scratch

The magnetic layer was destroyed and fine-dyspersated dust covered the plates and the hermetical area. The part of dust was accumulated on the filter, but the rest of dust was a potential threat. I had to wash up plates in a special solution, dry them up and install them into the donor disk hermetical area.

The following step was limiting the heads assembly access to the parking zone, otherwise donor heads could instantly burn down because of friction at the start. Then I had to center plates. I marked them with a micrometer first on the vertical axis, and then with regard to each other on the horizontal plane. Vertical centering demands using of the special device which registers rotation deviations and helps to eliminate them. Despite of all my efforts I did not reach ideal centering, and at starting the disk gave the following log out at the diagnostic port:

Reset
8192k x 16 DRAM
GALAXY - 1_Disk S-7A 12-08-06_16:41

Buzz HM SFI
!
$SFI
AMR

(P)SATA Reset
$SFI
AMR
$$$SFI

DiskAccess ReadSector EC=47 at ffffffff.00.0002

Failed sys sect. write! Nwt Er 13 RdWr 15f7b.00.0002
DiskAccess ReadSector EC=47 at ffffffff.00.0002

Read Ver Retrys
DiskAccess ReadSector EC=43 at ffffffff.00.0002

Read Ver Retrys
DiskAccess ReadSector EC=47 at ffffffff.00.0002

Read Ver Retrys
DiskAccess ReadSector EC=47 at ffffffff.00.0002

Read Ver Retrys
DiskAccess ReadSector EC=47 at ffffffff.00.0002

Read Ver Failure!
DiskAccess ReadSector EC=47 at ffffffff.00.022b
Failed sys sect. write! Nwt Er 00 RdWr 15f7d.00.022b
DiskAccess ReadSector EC=47 at ffffffff.00.0080
DiskAccess ReadSector EC=47 at ffffffff.00.0080
Unable To Load Overlay 01|000A

In such condition the disk was not ready on the interface. It was possible to read the user area, but only via technological port and at a very low speed, which could not satisfy the data recovery of volume over 100 Mb. I had to research the microprogram to display the disk to the interface and read it in the UDMA. Commercially available products have no such option.

The line "Unable To Load Overlay 01|000A" says that the disk cannot unload the 0-th overlay as the record was locked. The 0-th and the 1-st overlays are normally read physically.

Hence, for the line "Unable To Load Overlay" deleting the microprogram responsible for HDD basic options is to be edited. The ROM and application code fulfill the basic operations at the Seagate start. There are two ways of switching-off "Unable To Load Overlay" and the disc displaying at the interface. The rough way is one byte editing to stub the option, and the advanced way is the overlay demand analysis and the option expanded updating.

After entering the microcode necessary changes the disc was displayed at the interface and I had an opportunity to copy the user information needed. I packed the recovered files into multivolume archive and saved them at the special section of my ftp and sent uploading links to the customer.

My description helps to understand that data recovery from the scratched HDD was rather hard.