by TeraByte Support(PP) » Mon Aug 08, 2016 12:54 pm
sigi wrote:
> What puzzles me is that you still use if's. I thought the screenhots and the partinfo
> I had attached to my last posting have made it clear that the "overlapped
> partition" (I assume you mean /dev/sda3 i.e. Win7 on HD-0) still existed but has
> an unknown file system.
By "still exists" I think what was meant was that the partition was still in an intact state underneath the overlap. In that case, recovering the partition would be fairly easy. I seriously doubt the Windows partition is still intact, though.
> Question 1)
> ----------------
>
> > if the new 100 went over it and corrupted it
>
> What is "it" here? It cannot be the the last sector because that is some 70
> GiB later than the end of the 100 MiB (deleted by me in a hasty action).
"It" is the boot sector of the original Windows 7 partition (the one that got overwritten). When the new Windows boot partition was created it overwrote the beginning of the existing Windows 7 partition. Any data that got overwritten is lost. Using the backup of the boot sector (located in the last sector of the existing Windows 7 partition) may allow you to recover the partition and partially recover the data (anything overwritten is lost, anything corrupted is most likely lost, etc.).
> Question 2)
> ----------------
>
> > you can try putting it back
>
> Again what is "it" here?
"It" is the copy of the boot sector (from the last sector of the partition). The process would be to copy the backup copy of the boot sector to the first sector (original location) of the partition.
> Question 3)
> ----------------
>
> > So 1 - save start/end lba of partitions you think are good (they way it was)
>
> That is start/end lba of partiitions Num 1 through 9 in the below partiition table?
> All of the eight, and excluding Num 0 because it is not good?
You would make a copy of the last sector of the existing Windows 7 partition (sector 147458047). TBOSDT can be used to copy the sector (this can be done when booted to BIBM or TBWinRE).
When it comes to recovering corrupted partitions there are many ways to go at it -- some might work, some might not or even make things worse. Below is what I would try. Perhaps it will provide you some insight.
What I would do first is create an entire disk image backup of everything (include unused sectors). This will be a large backup and take time, but you would have a complete copy of the disk that could be restored for additional data restoration attempts, if needed. At the very least, I'd create a backup of the entire Windows 7 partition (including unused sectors) and normal backups of the other partitions. In any case, be aware the Windows partition, even if recovered to the point it's browseable and you can copy files off, will very likely not be usable for Windows. For example, you may be able to copy off your data files, but Windows may not boot or function (you'd need to reinstall).
Deleting and undeleting partitions can be done to see if the partition can be recovered that way. Note that making these types of attempts can write to the disk and may make further recovery attempts more difficult. In your case, it sounds like you just deleted the new 100MB Windows boot partition and didn't clear its boot sector as part of the delete. Then the original pre-existing Windows 7 partition remained on the disk as it originally was (same size, same starting location) -- only it's now corrupted and won't boot due to part of it having been overwritten.
[Note: You may wish to save the starting and ending sectors for the corrupted Windows 7 partition before deleting it (see next step, items 1-4, below).]
Using BIBM, if you delete the existing corrupted Windows 7 partition (do not use the option to clear the boot sector) and then undelete, does it find the new 100MB Windows boot partition? Or does it find the pre-existing Windows 7 partition? If it finds the 100MB partition again, then you would need to delete it and select the option to clear the boot sector. Then try to undelete again. Does it find the pre-existing Windows 7 partition? If so, can you access it (browse it, etc.)? From what you've described, I would assume not and you'd likely end up with the disk just as it is now (or without the Windows 7 partition).
The next step would be to try restoring the backup copy of the partition's boot sector. To do this, make a copy of the last sector of the partition and then copy that to the first sector.
1) Run TBOSDT (this can be from BIBM or TBWinRE).
2) Determine the Disk # to use. This is probably 0. You can run the command "list hd 0" to get a list of partitions on disk 0, "list hd 1" for disk 1, etc. Use the disk number in the following commands (0 is used below). Note that the Windows 7 partition won't show up in the list if it has been deleted.
3) Save a copy of the backup boot sector, run: copy sectors 0 147458047 1 bootsect.bin
(A copy of the sector will be saved to the bootsect.bin file in the current directory.)
4) Save a copy of the current "bad" boot sector, run: copy sectors 0 16065 1 badbsect.bin
(This assumes that LBA 16065 is the original starting sector for the partition.)
5) To copy the saved backup boot sector to the original boot sector location, run: copy sectors 0 16065 1 bootsect.bin /w
6) At this point, if the Windows 7 partition doesn't exist, use BIBM to undelete the space and see if it shows up. Otherwise, reboot. Then check if the partition is accessible.
If it doesn't help, you'll need to try some data recovery programs on the disk. As previously stated, they would need to look for file system and file information on the raw disk without regard to a partition.
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Note: The Windows 10 installer/updater will very likely make partitioning changes as part of the process. These changes may be expected (such as creating a boot partition if one's not found) or unexpected -- and almost always unwanted in multi-boot setups. In my experience, it's best not to count on anything partition related when Windows is installing/updating (I've seen quite a few different results from the same operation). I would create a backup image first if a drive must be connected and disconnect or disable drives not necessary for the install/update operation so Windows never sees them. If using EMBR partitions make sure the partition table is loaded in such a way that Windows won't be able to overwrite anything or create a partition (e.g. all partitions loaded, partition table full).
Paul Purviance
TeraByte Support