My hard disk develops bad sectors, n after surface scans the bad areas are marked.

However, once I issue Format and FDISK /MBR command, I see that all the previously marked bad sectors are gone.

Does this mean FDISK /MBR removes the history of marked bad sectors?
How can I overcome this if so?

If anything is is the format command removed the bad sectors. When you format the disk looks at previous sectors marked as bad an tries to re-read them. If successful it removes the bad sector flag and carries on.

There is also a section on hard disks reserved for re-mapping bad sectors. This is probably what the format has done. Once this section is full of remapped sectors then the problems really start.

If the bad sectors are in the area used by the MBR then you are looking at a potential disaster. If the bad sectors come back I would think about replacing the disk.

Stuart

I agree with StuartS. If your hard drive is developing bad sectors, it's time to replace the drive. The odds are very high that it will completely die before too long.

When you start getting bad sectors it's usually because the head(s) are starting to contact the platter(s). This causes particles to be scraped off. This in turn gets trapped between other heads and the platters and caused more damage. It's like a vicious circle.

Virtually all hard drives have a tiny percentage of bad sectors. All hard drives since very early IDE drives have a small percentage of sectors on the drive in a logically reserved area not visible to the user. Any bad sectors found by the manufacturer are marked as unusable and good sectors are assigned from the reserved sectors to replace the bad sectors. After you start using the drive, automatic routines built into the hardware logic of the drive find bad sectors as they are encountered and replace them with ones from the reserved sectors, and if there was any data on the bad sectors the data is moved to the good sectors that replaced them. To the user this makes the hard drive appear to be free from bad sectors all the time, as long as there are enough good sectors available of the reserved sectors.

However, if the drive is starting to fail the number of bad sectors will eventually become more numerous than can be replaced by the capacity of the reserved sectors, there are no more spare good sectors, bad sectors will be encountered by your operating system, and software that can test for bad sectors will find bad sectors.

The fact that the software is finding bad sectors probably means your hard drive is failing.

Check your hard drive with the drive manufacturer's diagnostics.
See the latter part of response 1 in this:
http://www.computing.net/windows95/...

If you don't have a floppy drive, you can get a CD image diagnostic utility from most hard drive manufacturer's web sites, but obviously you would need to make a burned CD, preferably a CD-R for best compatibilty, on another computer if you need to.

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"....once I issue Format and FDISK /MBR command, I see that all the previously marked bad sectors are gone."

If you use Quick Format, it doesn't check for bad sectors and true bad sectors will appear to be gone, but they're still there.

(NOTE that if you copy or clone a partition that has bad sectors marked on it to an error free drive, the locations of the bad sectors on the original partition are copied too, and will be FALSE bad sector locations on the drive copied to. That is hard to correct, other than by deleting the partition, especially if the partition is NTFS - only Vista has a fdisk switch that can correct that situation.)

"Does this mean FDISK /MBR removes the history of marked bad sectors?"

No. It doesn't alter the partition table entries.
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FDISK /MBR rewrites the Master Boot Record
http://support.microsoft.com/kb/69013

Quotes:

"The MS-DOS Fdisk utility usually updates the master boot record (MBR) only if no master boot record exists. Repartitioning with Fdisk does not rewrite this information."

"Fdisk has an undocumented parameter called /mbr that causes it to write the master boot record to the hard disk without altering the partition table information."

"NOTE: The fdisk /mbr command only re-writes the MBR on the system drive (DISK-0) using BIOS calls. You cannot specify any other drive for the fdisk /mbr command to operate on other than DISK-0."

Note that it states the fdisk /mbr command doesn't alter the partition table information - therefore any sectors already marked as bad will still be marked as bad after running fdisk /mbr.
When you use software such as chkdsk or scandisk or Norton Disk Doctor etc. in Windows to test the hard drive and it finds bad sectors, it flags (marks) the locations of the bad sectors in the partition table so that they will not be used by the operating system (if you actually fix the problem - e.g. use chkdsk /f or chkdsk /r), and if there was any data on the bad sector(s) an attempt is made to copy the data to good sectors, which may or may not be successful.

When you use fdisk to partition a drive from scratch or to re-partition a drive, with no command line switches, or with most if not all command line switches other than /mbr, it throughly tests all the sectors while partitioning and if if finds iffy or bad sectors it re-tests them many times, which will slow down the time it takes to partition a little or a lot depending on how many iffy or bad sectors are encountered, and if a sector is found to be unreliable or bad it flags (marks) the locations of the bad sectors in the partition table so that they will not be used by the operating system.
When you subsequently Format the drive it takes a minimum amount of time because the bad sectors are already marked.

Simlarly, if you do a Full Format, rather than a Quick Format, of a hard drive, it throughly tests all the sectors while formatting, making it slower than a Quick Format, and any bad sectors found are flagged in the partition table and are not used. A Quick format will not check for bad sectors - I never use Quick Format for that reason.

E.g. Windows 2000 or XP Setup will allow you to select Quick Format of an existing partition.
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I've had a few hard drives that developed some visible bad sectors but after that the number of them did not grow, but that is relatively rare.

If the manufacturer's diagnostics find only a small number of bad sectors, and if they do not appear to grow in number (no more appear when tested shortly after running fdisk or a full format), you could try using the manufacturer's "zero fill" or so called "low level Format" utilities (often actually a zero fill utility as well) in their drive preparation utilities - that will test the drive for bad sectors while doing that and set the number of visible bad sectors to zero again, if there are good sectors available from the reservered sectors that weren't assigned automatically for some reason, or if there are none left, possibly reduce the total capacity of the drive by the amount the bad sectors occupied.
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In my experience there's usually nothing wrong with the mechanical parts of the drive that has failed - it's usually the logic board that has failed, sometimes made obvious by it having a larger chip that is obviously overheating (you can't keep a finger on it for long).

Thanks for the detailed information.