HDD Raw Copy and HDDScan disagree on number of bad sectors

[Leolo]

Hi people,

I'm using two great tools from this site: HDDScan 3.3 and HDD Raw Copy 1.10

I'm currently in panic mode because one of my drives, a Western Digital Red WD20EFRX has defective sectors, and I'm unable to view its contents from Windows. Windows thinks it's a RAW disk and cannot mount it

I tried TestDisk 7.0, and it detected a good backup copy of the exFAT boot sector, but it's unable to copy it over the main boot sector. It gives me a "write error" and cannot continue.

But there's something I don't understand. When I run HDDScan in read or verify mode, it detects approximately 800 bad sectors (starting from sector 2048 onwards). Every time I run it it detects a different number of bad sectors (sometimes 790, sometimes 810, etc)

However, HDD Raw Copy Tool only detects a single bad sector (just sector 2048, nothing else), and the rest of the sectors are copied fine.

Why is that? Who is correct? Is HDDScan overreporting the number of bad sectors? Or is HDD Raw Copy underreporting them?

Who should I trust more? Who is lying and who is telling the truth!?

[fzabkar]

However, HDD Raw Copy Tool only detects a single bad sector (just sector 2048, nothing else), and the rest of the sectors are copied fine.

Are you saying that you managed to clone all of the drive apart from a single sector? If so, then repairing the clone should be very easy with a tool such as DMDE.

[lcoughey]

Clone the drive then copy the backup BS to 2048 on clone.

[Leolo]

Hi,

I'm afraid that neither of them is telling the truth

HDD Raw Copy reported only one bad sector, but it's not true. There are several more bad sectors. But the number reported by HDDScan (sometimes 803, sometimes 790, sometimes 810) isn't true either.

I suspect that HDD Raw Copy found a bad sector in LBA sector 2048, and automatically jumped over a whole block of several consecutive sectors, without notifying me

I guess there must be a confusion somewhere because of my drive having 4096 byte physical sectors but reporting itself as 512 byte logical sectors (It's an AF drive)

[Leolo]

By the way, DMDE is unable to recover the boot sector from the cloned drive. The option appears greyed out. TestDisk is also unable, cannot find any backup boot sector.

I've plugged the original drive again, and both programs (DMDE and TestDisk) are perfectly able to locate the backup boot sector, but neither of them is able to overwrite the main bootsector in sector LBA 2048 (both of them give an error saying "write error")

I'm going to try Runtime's Disk Explorer and report back. I'm crossing my fingers!

[fzabkar]

Why not use DMDE to copy 1000 sectors, say, from 2048 to 3047? DMDE gives you a range of error handling options.

Tools -> Copy sectors

Parameters -> Reverse Copy

I/O Errors
- 1 auto retry
- skip I/O errors

[lcoughey]

You cannot and should not be trying to fix the file system on the original...as it has bad sectors. If you insist on doing this yourself without a decent hardware imager, you should try gnu ddrescue to get the best copy of the drive possible. Then, as I said earlier, try to fix the file system on the copy...or just recover the data from the copy to another healthy drive.

[fzabkar]

@Leolo, as yours is an AF drive, then logical sector 2048 will be the first sector within a physical sector comprising LBAs 2048 - 2055. AISI, writing to a single bad logical sector would be impossible. Instead you would need to update all logical sectors within the corresponding physical sector. That is, the drive would normally read the entire physical sector, verify its ECC, update those 512 bytes corresponding to the logical sector, recompute the ECC for the physical sector, and then write back the entire physical sector (read-modify-write).

That said, DMDE should throw up read errors if you try to access any sector in the range 2048 - 2055. AISI, it follows that the following statement makes no sense.

However, HDD Raw Copy Tool only detects a single bad sector (just sector 2048, nothing else), and the rest of the sectors are copied fine.

BTW, if you choose DMDE to retrieve the bad sector(s), I would configure it to skip 7 sectors (or is it 8?) on error.

AIUI, a bad LBA would normally be reallocated to a good spare sector after writing to it, but only if all 8 logical sectors were updated at the same time. This would explain your write error.

I tried TestDisk 7.0, and it detected a good backup copy of the exFAT boot sector, but it's unable to copy it over the main boot sector. It gives me a "write error" and cannot continue.

I'm familiar with FAT12/FAT16/FAT32, but I've never examined an exFAT volume. FWIW, in a FAT32 volume, logical sector 0 is the boot sector and sector 6 is the backup. Therefore both sectors would exist within the same physical sector, so if one were unreadable, then the other would also be unreadable.

Could we see HDDScan's SMART report?

Last edited by fzabkar on May 12th, 2016, 16:22, edited 1 time in total.

[Leolo]

I've been looking at the logs in the Event Log, and judging by the errors logged while I tried to clone the drive:

"The IO operation at logical block address 0x800 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x801 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x802 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x803 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x804 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x805 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x806 for Disk 1 (PDO name: \Device\00000025) was retried."
"The IO operation at logical block address 0x807 for Disk 1 (PDO name: \Device\00000025) was retried."

I think that the probably correct number of defective sectors is 8 logical sectors (which means 1 physical sector).

I'm a bit disappointed with the HDD Raw copy tool, because it clearly skipped all those sectors. I inspected the cloned drive in Hex mode using DiskExplorer and confirmed that those eight sectors were blank (all zeroes) in the cloned drive

So, what I ended up doing is just reading those eight sectors one by one using Runtime DiskExplorer and pasted them into the cloned drive. (it still gave me read errors, but after a few tries it could copy most of them)

Afterwards, both TestDisk and DMDE were able to see the full filesystem on the cloned drive (even though Windows still stubbornly refused to mount it, complaining about corruption in the filesystem) and I could copy all the files and folders to a third drive. Yay!

Thank you lcoughey and fzabkar, for the suggestions and the info! I'm keeping the DMDE tool in my arsenal, I didn't know about it before and I find it much easier to use than TestDisk.

Kind regards.

[Leolo]

Could we see HDDScan's SMART report?

Argh, I can't I forgot to save it, and after recovering all the data I've used Western Digital's WinDLG 1.29 to repair the bad sectors. Now the drive has remapped them, and shows no error at all on HDDScan, sorry!