sir,

I want to know that if i purchase a second hand hardisk then how could i know that seamap software is used on it to hide bad sector from a customer....plz tell me how can i identify to avoid loss.

Thanks alot!!

Syed Fahad Hussain

I'm not familiar with that one but it looks to be an old seagate low level format utility. Among other things it's going to erases the bad cluster list from the drive. So it doesn't really hide them.

Then you'd partition and format the drive. The formatting process may very well re-find and mark the bad spots again. But often you'll end up with less bad spots than before you ran the LLF. This is because sometimes, for whatever reason, spots get marked bad that are really good. Or maybe the spot was originally marked because it was weak but somewhat useable and formatting didn't pick it up again.

LLF utilities supplied by the drive manufacturer's pretty much were discontinued as IDE drive got to around 1 gig. That's because those drives were less likely to tolerate a LLF and would often end up being damaged.

Unfortunately there's no way for the typical user to tell if an LLF has been run on the drive. Perhaps the manufacturer could but I don't know that for sure.

I suppose if you're uncertain about the drive you could demand to test it before buying or insist on a warranty.

Since a factory new drive may have bad sectors, how do you determine if the bad block table was rewritten?

Virtually all hard drives have a least a few bad sectors, but they are designated as not to be used by the manufacturer of the hard drive when the drive is prepared, and for except the earliest IDE drives and most if not all of the MFM and RLL drive controller cards and drives that came before them, the hard drive has automatic routines that detect any new bad sectors as they are found and replace them with good sectors on the fly, using spare sectors not visble to the user reserved for that use that amount to a small percentage of the sectors available on a drive, so the drive normally always appears to be free of bad sectors to the user and the operating system. There is no problem unless a bad sector is not being detected by those routines, which is rare, or unless the drive is failing and the spare sectors available to replace bad sectors have all been used up and any new bad sectors are visible to the operating system, or can be detected by chkdsk or other utilities.
Usually when you run a so called low level format on a drive these days, what it actually does is to write zeros to all the sectors on a drive (as does a zero fill utility), and often while doing that if it finds any sectors that are not marked as bad when they should be, it will replace them with good spare sectors if available, or sometimes if there are no spare sectors available it will mark the bad sector(s) as unusable and the total capacity of the drive will be reduced by the amount of space the bad sectors occupy.

"....sometimes, for whatever reason, spots get marked bad that are really good."

One way is if you copy a partition from one drive to another, or to another location on the same drive, the locations of any bad sectors found by the operating system on the original partition are copied to the second drive or location as well. You can't get chkdsk in previous to Vista and most other utilities to mark false bad sector locations as good.
I was searching for info about that yesterday for a copied NTFS partition.
You can use a disk editing utility, details here:
http://www.djkaty.com/drupal/ntfsba...
or also found there is:
"If you are using Windows Vista, there is a new option in chkdsk - chkdsk x: /b - which will re-evaluate all the bad sectors on your drive and remove non-faulty sectors from the list. Please use this instead of the methods below if you have access to Vista!"

- you can use linux utilities, along with a linux boot disk if you're not running Linux:
http://wiki.linux-ntfs.org/doku.php...

- or the freeware or trial version of this program, in various operating systems:
http://www.dfsee.com/dfsee/history.php