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Hi All,

I want to know the basic difference between erasing and formatting an hard disk drive from sector point of view.

As u all know that first sector is called MBR(Master Boot Record).As far as my research is concerned i came to know,In erase operation the data on disk is fully erased including MBR.But in cased of format MBR and partition is left out and rest every sector is erased.
Looking for your suggestions.

Regards,
Ravi chobey

Format creates a file system on a partition. It does not "clear" any sectors at all (it just overwrites the sectors that store file system information and metadata) If you want to get rid of all data (all data and not all files; if you want to delete all files just overwrite the entry in the partition table or the file system superblock / root directory) you will have to write zeros to every sector of the partition.

The MBR contains partition information for the drive. A drive can (usually) have up to 4 partitions.

So: you can erase or format either individual partitions, or the entire drive.

Erasing a partition or complete drive almost never means writing 0's to every sector. That would take a VERY long time. Erasing a partition just means overwriting all of the filesystem information on that partition, as Korona said. "Erasing" a complete drive just means overwriting the MBR.

Formatting a partition means erasing the partition (see above) and then writing a new set of filesystem information to the partition.

Formatting a complete drive just means writing a good MBR to the drive,
unless you are talking about SCSI disks. SCSI disks have a "low level formatting function" that should be called before writing an MBR. But I know that you are not using SCSI disks.

bewing wrote:SCSI disks have a "low level formatting function" that should be called before writing an MBR.

Old (outdated) knowledge. Modern SCSI drives require a low-level format only once (at the factory), and in fact most of them don't even interpret the corresponding command anymore, but merely skip it.

The easiest way to erase a drive (write zeros to the whole lot) is with SeaTools, a program made by Seagate to test disks. You can download an ISO from their website. It's called SeaTools for DOS (but comes as an ISO).

Yayyak wrote:The easiest way to erase a drive (write zeros to the whole lot) is with SeaTools, a program made by Seagate to test disks. You can download an ISO from their website. It's called SeaTools for DOS (but comes as an ISO).

I have a copy of SeaTools burned onto a CD, it's rather helpful actually, it can repair(remap) damaged sectors on both Segate/Maxtor drives. (Great way to extend a drives life for a few more years.. instead of tossing it away, as most people tend to do.).

Erasing a drive is not writing all zeroes per se. If you want to erase it safely (so that no data is left behind), you must write semi-random garbage several times to each sector.


JAL

It's a myth that you need to overwrite a sector more then a single time, I've yet to find evidence that data can be restored after that.

Blind faith is blind faith, until I find a document showing proof data can be restored.. one pass will suffice, any more simply means you're paranoid..

If anyone's still paranoid, have a look at Darik's Boot and Nuke

Cheers,
Adam

Brynet-Inc wrote:It's a myth that you need to overwrite a sector more then a single time, I've yet to find evidence that data can be restored after that.

Blind faith is blind faith, until I find a document showing proof data can be restored.. one pass will suffice, any more simply means you're paranoid..

That's shifting the burden of proof! Rather, I should say: you have blind faith in your method of erasing data. Anyhow, IIRC one pass should suffice for most day-to-day usage, since the time and equipment needed (i.e. electron microscope), are beyond the means of an average identity theif! Unless the data is likely to be a target of industrial espionage or law enforcement, there is little point in 'securely' destroying data, unless for hobbyist enjoyment sake.

OScoder

IMHO it should suffice, whether or not anyone has a electron microscope or not, to do a 3 pass. first writes all zeros, second writes all ones, and third zeros or garbage.

Wikipedia says that it might be possible to recover data from old hard disks: Gutmann method
It also says that it's unlikely that data can be restored from modern hard disks after the sectors have been overwritten with zeros.

Its possible to get data of a disk thats been erased nulled in two main ways, though these would only be used by law enforcement agencies to recover data of confiscated computers:
1) The head is always slightly inaccurate and its possible with a reader that is much more accurate to read of the 'edge' left which still contains the data.
2) magnetism measurements, the head doesn't completely neutralize the different magnetic polarizations, so there is still a slight difference in polarity between a zero that's been overwritten by a zero and a one thats been overwritten by a zero (and vise versa). Though again this uses equipment out off the reach of the average person...
Jules

To permanently erase data:

Melt the actual disk.

Heat removes magnetism, and melting deforms it into something you can't read anyways.

Combuster wrote:To permanently erase data:

Melt the actual disk.

Heat removes magnetism, and melting deforms it into something you can't read anyways.

hehehehe....

Jules