4 ms·

I'm pretty much a total novice with low-level aspects of storage, but if this is essentially writing junk to the windows bootloader or something to preveny boot

I'm pretty much a total novice with low-level aspects of storage, but if this is essentially writing junk to the windows bootloader or something to preveny booting to OS, couldn't one just plug the HDD as a non-ROOT drive to another PC and recover some of the important files? I've seen people successfullu do this before after their super old ROOT disk gets corrupted exactly where the windows bootloader is...

barrkel 9y ago
No, that wouldn't work; you'd have to scan the disk for partition information to reconstruct it, or otherwise guess reasonable values (backup being best).
- ptero 9y ago
  Which does not seem like a particularly difficult task for me. Not quite trivial, not particularly quick, not guaranteed to work 100%, but for main partition types the task should be suitable as an undergraduate CS assignment. However, as you say, having data backed up is a better solution.
jaclaz 9y ago
Two cases: 1) MBR "style" partitioning: in first sector of the disk there are at most 4 addresses pointing to the partitions on the disk (which may consist of primary partitions and as such volumes, or one of them may point to an extended partition that has a chain of EMBR's pointing to logical voluems inside it) It is trivial nowadays, using freely available software, to search the disk for the volumes and rebuild the partition tabel in the MBR. 2) GPT disk: The first sector is only a "protective MBR" where in the partition table there is only one entry spanning from sector 2 up to the end of the disk (this can of course be rebuilt in no time). The issue is that the GPT partition table (i.e. addresses of the volumes) is in the following sectors (and the overwriting of 24 or 9 sectors will destroy the data for good, as normally only two sectors are used) and due to the peculiariries of the way these GPT entries are stored it is slightly more difficult to rebuild the data (though the actual volumes on disk can anyway be found and retrieved/imaged). But - IMHO more or less the only good thing about GPT - the MBR and all GPT tables are automatically backed up to the end of the disk, so there is usually no need to rebuild anything, it is just a matter to properly restore the entries from the backup.

barrkel 9y ago

No, that wouldn't work; you'd have to scan the disk for partition information to reconstruct it, or otherwise guess reasonable values (backup being best).

ptero 9y ago
Which does not seem like a particularly difficult task for me. Not quite trivial, not particularly quick, not guaranteed to work 100%, but for main partition types the task should be suitable as an undergraduate CS assignment. However, as you say, having data backed up is a better solution.

jaclaz 9y ago

Two cases: 1) MBR "style" partitioning: in first sector of the disk there are at most 4 addresses pointing to the partitions on the disk (which may consist of primary partitions and as such volumes, or one of them may point to an extended partition that has a chain of EMBR's pointing to logical voluems inside it) It is trivial nowadays, using freely available software, to search the disk for the volumes and rebuild the partition tabel in the MBR. 2) GPT disk: The first sector is only a "protective MBR" where in the partition table there is only one entry spanning from sector 2 up to the end of the disk (this can of course be rebuilt in no time). The issue is that the GPT partition table (i.e. addresses of the volumes) is in the following sectors (and the overwriting of 24 or 9 sectors will destroy the data for good, as normally only two sectors are used) and due to the peculiariries of the way these GPT entries are stored it is slightly more difficult to rebuild the data (though the actual volumes on disk can anyway be found and retrieved/imaged). But - IMHO more or less the only good thing about GPT - the MBR and all GPT tables are automatically backed up to the end of the disk, so there is usually no need to rebuild anything, it is just a matter to properly restore the entries from the backup.