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 Post subject: How to Shield Bad Blocks with P-list in Seagate HDDs
PostPosted: September 5th, 2016, 23:09 
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Joined: June 26th, 2014, 5:08
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Location: China
For repairing of Seagate HDD, if the head is physically damaged to the extent that it has to be shielded, the operations for bad head shielding is required, if the malfunctions are resulted from Zone damage, we have to shield bad zones. The circumstances mentioned above will not be involved in common approaches to repair bad tracks. There are two stages for common approaches to repair bad tracks:

1. Add bad blocks into V4(ALT table), then transfer the blocks already added into V4 to V40(non-residential G-list) through translator regeneration.

The first approach is to add LBA into V4 through terminal commands, then regnerate translator by m0,6,3,,,,,22 by which the defects are added into V40. However, there are certain disadvantages with the approach described here, one of which is the relatively insufficient capacity of V4. At present, the approach is well supported by the Seagate HDD repairing softwares on the market ,some of which is merely able to add bad block into V4 through terminal command, some of which with a hardware could have the operation mentioned above executed under SATA mode which makes the process go faster .

2. Add bad blocks into V40 directly.(Non-residential G-list)

In consideration of the inconviniences incurred by approach mentioned before, we exploited another approach to deal with bad blocks, which is to add bad blocks into V40 directly without being troubled by first adding them into V4. The operation would come into effect after the translator regeneration by m0,6,3,,,,,22. There is no such terminal command to add bad blocks directly into V40, so we might need some auxiliary softwares to achieve it. The softwares on the mainstream HHD repairing market can well support this function.

Nonetheless, this approach is not optimal either, there are conspicuous disadvantages as well, for example, the defects saved in V40 is not residential, if the parameter in commad is incorrect, the defects might be cleared inadvertently, and if there are too many defects, the space required to store them would exceed the capacity of V40, thus the operation might fail.

In fact, the best way to sheild bad blocks is to add them in to V10(P-list) whose format is way more complicated than that of V40. Instead of adopting common sector address,the address of P-list defects is expressed in SFI. To add defects into P-list,we have to first convert LBA defect addresses to SFI form.

Based on the theory described above, we found a 3rd way to sheild bad tracks:

3.Add bad tracks into P-list directly.With relatively larger capacity,better shielding effect and less possibility of being inadvertently erased, Adding defects into P-list is the best way to repair bad tracks.



MRT adds a new function for HDD repair in the latest version of software. With this function, users can add bad tracks to module 03 directly and then recalculate translator to make the modification valid. In the past, bad blocks can only be added to G-list, now it can finally be added to P-list directly. The operation time becomes much shorter and success rate is greatly improved. Due to the complication of P-list address format, MRT is the only software that can add bad blocks to P-list.

Step 1: Scan the HDD and click “Whether to save the bad block into the defect table file ”. Please note that if there are a lot of bad blocks in the HDD, an option “Skip bad block ” can be clicked to increase the scanning speed. And users can set reasonable skip size, and then click “Add skipped sectors to defects”. When users set these parameters, they can start scanning the whole HDD and save bad block into defect table files. (reference pics are showed as enclosed pic1&2)

Step 2: Write the defect table files into Module 03 of HDDs.
First , open Module 03 of the HDD and select the HDD model between Seagate Generation 11 and higher than Generation 12. If users selected the wrong model, module 03 cannot be read. If users are not clear about the model, they can try one by one to see which one is the right model. Now users can add the scanned defect files into P-list. (reference pics are showed as enclosed pic3&4)

In P-list editor, users can add bad blocks into P-list if they click “LBA” on the tool bar. MRT software will change the LBA address format of bad blocks files to P-list address format.

Step 3: regenerate translator.

The new defect items will not take effect when the two steps above are finished because they are just added into Module 03. Users need to regenerate translator to make them effective. Both the parameter m0,6,3,,,,,22 and m0,6,2,,,,,22 can be used to regenerate translator.

Step 4: Erase the whole HDD.

HDD can’t be used unless it is erased. The purpose of this step is to erase all the sectors. There are several ways to do it . The first one is to do low-format with parameter m0,8,3,,,,,22. The advantage of low-format is that it can be done automatically with an external power supply for hard drive, which makes it unnecessary to occupy the interface of MRT. The second way is to scan HDD in write mode. It sometimes occur that low-format gets stuck at some point. In this case, users can scan the HDD in write mode. It can also erase sectors but needs to occupy MRT interface. The third way is to choose “security erase data ” under “security subsystem”, which won’t occupy MRT interface after being started.


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