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program that can list corrupted blocks?

V

venm11

2[H]4U
Joined
Oct 6, 2004
Messages
2,236
hey y'allll - I'm attempting to partition around some bad blocks but I can't seem to get any programs to give it up (including hitachi dft). Does anyone know of a way to get a list of lba addresses for bad blocks from a surface scan? Or some program useful to this end.

Also, seeing relocated blocks would be useful, or some way to understand the corrections made by various progs.
 
In any drive made in the last decade you should not be seeing a single bad sector at the filesystem level because the drive automatically reallocates bad sectors with spares that it has reserved for this case. If you see bad sectors at the filesystem level the drive has run out of spares. I consider this a dangerous situation. Either RMA the drive (if it still has a warranty) or spend $50 to $60 and buy a new 1TB drive.
 
I believe that you wish to do can be done in linux (you can boot from a linux live CD and access all the HD utils and the command prompt). But I'm with drescherjm. If you've got bad blocks like that, consider a new HD. What does SMART say?
 
SMART says 5 reallocated sectors, 0 uncorrectable. Everything else is perfect, except cycle count but this is a laptop drive. DFT originally reported a possible impact, but I'm not sure where it recorded that.

Even without repairing them, I was able to copy the disk (with an error override) and get almost total recovery. However, no matter what tools I use to "repair" it, the disk still gets stuck on those areas (only know the first LBA). I had another disk recently (seagate) which was completely unusuable, and several programs "repaired" with no success, until one did and now it's operating normally, with the OS and everything - what could have been different?

New hard drive is already up and running. I have a purpose in mind for this one, if I can get it to a useful state.
 
Reallocated sectors are hidden from your OS; Current Pending Sector in your SMART output is ACTIVE bad sectors; and you fix them simply by overwriting them.
 
sub.mesa said:
Reallocated sectors are hidden from your OS; Current Pending Sector in your SMART output is ACTIVE bad sectors; and you fix them simply by overwriting them.
Click to expand...

So they must be reallocated at the CHS level, which tend to be a proprietary algorithms. It's hidden by the indirection, but I don't see how concealing it is a good idea. Surely the manufacturer's tools can request this info from the controller?

So.... a bad sector is remapped. What other scenarios are there? If it's remapped to another bad sector, does it need another pass to detect and "repair" those problems, or is that done recursively in the initial repair?
 
CHS is legacy; this all gets emulated, it has no true relevance anymore. CHS gets translated to LBA x (number), the LBA is the virtual address space. Like SSDs, HDDs can represent a different LBA to the OS than it internally keeps. HDDs only do this for bad sectors, SSDs do this all the time so sector 1 may be indeed sector 1 physically or some random remapped sector.

Bad sectors develop as Current Pending Sector in your SMART data. This will trigger deep recovery when the sector is accessed. This can take up to a minute, and may fail if is its really bad. In that case, you can overwrite the sector, forfeiting recovery abilities. Once you write to a current pending sector, it will either keep using that sector if it its not really bad physically but it just couldn't read it the last time (decaying electron charge perhaps); OR if the bad sector is really bad, then it will remap to a reserve one from its reserve sector pool (thousands of reserve ones).

The OS cannot know this and thus would never have to deal with this. But if you have Current Pending Sector then that is very bad!
 
I meant that it simply changes the CHS mapping, and that indirection is owned by the controller alone.

So... you present interesting info. So when software "repairs" issues, it simply tries to read and rewrite the sector, and lets the drive decide whether to remap it? Or are there specific ATA commands pertaining to this? Perhaps proprietary ones that only the mfr's software can use? I'm still trying to figure out why one program would succeed where others failed.

The program gary mentioned appears to have a feature to report the bad LBAs, which is what I wanted, although I'm suspicious of it because I can't figure out why the program exists because it does all the same stuff the others do. In other words, what could possibly make any program unique in their ability to recover data or hard drive usability?
 
Grab a Linux live disc and overwrite (destroy) the whole hdd with: (have a backup first!!!)

# dd if=/dev/zero of=/dev/your_hdd bs=1048576

Then scan it again. If it still hangs, it's junk. If it doesn't hang, it still may be in the process of failing. You'll have to take the age and history of the drive into account for your own judgment. There's probably a way to read and write the same data, in the hopes of being non-destructive.

Fixing is simply writing the sector, and the drive takes the opportunity to remap to a fresh sector behind your back. Once it runs out of spare sectors, you have failed sectors that you can't get rid of.
 
A friend of mine recently tipped over his WD MyBook while it was running, and a scan with HDAT2 showed thousands of errors, spread around 6 areas throughout the drive. They disappeared from view after the drive was zeroed out.
 
That sounds like the head went flying across the platter as a write was in progress ... bad timing on the tip over!!
 
Also worth mentioning the commercial software SpinRite by GRC. Written in assembly, it can fix many bad sectors and recover them. It does not run on all BIOS systems though.
 
garymkrieg said:
I don't know if this is what you need but take a look at HDD Regenerator.

Gary
Click to expand...

Thanks for this tip, Gary, this program gave me the info I needed to partition around them. It attempted to repair and claimed itself to be successful (remapping all the sectors), but the hitachi DFT tool gave some inconsistent pass/fail results after that.

Ultimately, the drive appears to be working well but will have to be considered untrustworthy. Still, not bad for a lost cause.
 
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