HDD Bad sectors

[jinxy]

Why would you need to know where the bad secctors are??..............You don't control where data is stored, the OS does.

Of course it would be inportant to see if a HDD is developing bad sectors, simptom of HDD fiesk up.

[mrg81]

Spinrite will give the particular sector that is marked bad, to some extent it does help me, But it's not a free ware, neither they have a trial version. Spin rite also says (manual) says that
the data from the bad sectors can be relocated to the safer area. I am assuming that the safer area is the spare sector list, i.e. is where the remapping occurs. But it doesnot give me the list of the spare sectors.

Also I will give WD a call, let see what they have to say.

Thanks,
MRG.

[mrg81]

AFAIK the bad sectors are hidden from the OS as well. The bad sectors list is maintatined by the HDD, it is still not clear whether the bad sector list comprises of both the p-list(factory defects) and the g-list(growing list of sectors) or just the g-list. when the sector is marked bad , the HDD maps that bad sector to the spare sector(this is known as reallocaton count0, so if you see the SMART attriburte number 5 , it will give the reallocated sector count.

[rider_royal]

Just a question as i read it somewhere on this forum and net also but cant find that now or recall of what i am asking:

If a HDD develops BAD sectors, and after the disk checking is done as instructed above. How much time we can expect in normal condition that it will work OK, or once bad sectors develop they grow like cancer (with an expected time limit unless miracle or cure is there)?


Also one case if my windowsXP with all tools at right place and no cracked softawre or anything else(checked virus n malware with every tool mentioned) chkdsk done in complete sense, start to get real slow in when something on harddisk is accessed like clicking a file, but works fine when once that file is opened.(so bad sector expected) So, can it be cured ? means can these bad sectors can be earmarked and hence denied to be used by OS?

thanks guys and if this question deserves to be in new thread in hardware, tell me. thnks again

[mrg81]

For Rider_royal: Are you sure that your HDD has developed bad sectors? Did chkdsk report any bad sectors, try drive sitter or any other utility first to find out if there are any bad sectors , if yes then try HDD regenerator to recover from bad sectors, there are many other utilities that will just correct the bad sectors.

Thanks,
MRG.
`

[nihil]

Well, mrg81 , the only way you will get that information is from the HDD manufacturers themself. I would bet the answers are not consistent

And if you are to have a better chance than a snowball in hell, you will have to be a lot more upfront about your reasons and objectives. Nobody whose livelihood depends on those manufacturers is going to disclose the information without authority.

You have no right to this information...................you have to beg it, which means you have to be trusted.

That is life my son.....................learn to live it

[mrg81]

Well, i did find out one tool, I got the name atleast from the following paper. These are a part of my research on HDD forensics.

http://www.usenix.org/publications/l...chindler_html/

Now, i have to find out where I can download it.

Thanks,
MRG.

[nihil]

mrg81

That is more like it!..................it is not that I did not trust you, or wanted to steal your research, it is just that I felt that you were going the wrong way about it.

You need some of the HDD people on your side. If you sweet talk them, and they are happy that you are not going to dump them in the crap, they will help you?

I recommend a "wet Monday morning, Friday after lunch" approach.............that is when staff are bored and will do anything rather than real work

You might get some bona fides from your principal or whatever and make it an official enquiry from your college............that cuts a lot of ice

I have had great support over the years from commercial, government and military institutions..........the secret is to act dumb and ask for help

Good luck!

[Relyt]

rider_royal

So, can it be cured ? means can these bad sectors can be earmarked and hence denied to be used by OS?

Bad Sectors commonly come in two flavors and you could be suffering from either one or both.

Physical Structures (tracks, sectors, etc) being damaged and Logical Structures (tracks, sectors, etc), being damaged. Although the verbiage difference between the two is obvious, generally more than one or two of either flavors is a huge hint to immediately attempt to recover all the data you can from the HDD.

“Physical” Bad Sectors are actually physical in nature as the name indicates. Most likely magnetic errors. May be able to be mapped out. May also be an indication that you need a new drive, or might have to send it to the factory if under warranty.

“Logical” Bad Sectors, on the other hand, could have been caused by a virus, malware or some OS going fubar on you. AV’s and other remapping utilities may be able to assist here, however using a “zero-fill utility” will most likely cure your drive of it’s ails. I usually make the sick drive a slave and zero-fill, repartition, complete a “high level format”, and then place the bugger back into service. On every occasion, the “Logical Bad Sector(s)” problem was resolved. Since I listed "high level format", just in case:

Format: the phrase you may not understand correctly.

High-Level Formatting: This is the “format” or meaning that flows off the tongues of most. It creates the logical structures on the HDD and makes the disk ready to place the OS near the first sector. Completed after creating volumes (partitioning) on the HDD.

Low-Level Formatting: Creates the actual physical structures on the HDD. Done only once at the manufacturer because of the complex nature of the structures on the modern drives. The older drives had the same number of sectors on the outer tracks as they did on the inner tracks. With the advance in technology we now have more sectors on the outer tracks than the inner ones. Google “Zoned Bit Recording” for an explanation. I would question any utility that claims it can complete a low-level format of a HDD while it’s on your computer. The drive controllers will laugh at the futile effort because they are designed not to allow it. Additionally, if it could be done, it would erase the “servos” on the tracks and the poor HDD Head would take a vacation because it wouldn’t know where to go to find the tracks. So read the documentation carefully before using. It may well be just a remapper.

There are some utilities that claim they can repair/regenerate the bad sector without damaging the logical structures. One I know of has a Free Trial (will assist with the first bad sector). Additionally it claims to be able to detect the different type of sector faults as well.

HDD Regenerator 1.42


Anyway hope that helps some.

!~cheers~!

[Maestr0]

Boot a linux cd, then use badblocks.

"badblocks -nv -o logfile /dev/hddX"

As Relyt touched on, most drives will attempt to remap bad sectors when they encouter an error. If the drive cannot read the sector to remap it, you will need to rewrite it to force it to remap. (you can just "dd" zeros onto the sector)

-Maestr0