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Interrupting Hard Drive Wipe/Format

8K views 6 replies 4 participants last post by  Migs123 
#1 ·
I have an older version of Partition Wizard to wipe my hard drive. I decided to wipe it using ones and zeros, instead of just using ones OR zeros, and its going to take over 3 hours. Could I just interrupt the wipe and just redo it using a quicker method?
I googled "interrupting a hard drive wipe" and it yielded some results from which I read different takes on this. I also thought it may be worth discussing here.
I know that if you interrupt a low level format you can cause damage (although I am not sure why)
So in my understanding Wiping is simply writing data to the sectors replacing old data, so if I just stop it, it will simply stop WRITING data so it shouldnt affect anything right?

What does a low level format do that makes it so dangerous to interrupt?

Low-level formatting creates the physical format that dictates where data is stored on the disk.
So what does it "format"? Is the term still "wipe"?
How does it format the stuff that dictates the format? Does it go underneath the sectors?
Thank you
 
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#3 ·
A Low Level Format is basicaly changing the binary index Value for each unit on each track to 0.
Think of it like this, you have 4 walls made out of bricks, each wall is behind the other and each brick is opposite the brick in the wall in front. Each Brick holds one bit of data and has a unique binary number that makes up a Register ID. If the Register ID is set at 00-00-00-00 that indicates that the unit is ready to accept the data write procedure. A Low level Format does this to all unit's in a hard drive. However changing the Register ID for a Data Unit does not mean that the data unit is empty.
This is why ending a low level format can be so dangerous.
A Data unit is a electrolytic capacitor connected to a 3.7 ohm resistor at the positive the resistor connects to the emitter of a transistor and the collector of the transistor connects to the negative of the next capacitor (the next data unit), the base is supplied by a common source connected to all the transistors in the circuit. This is how a Ram Circuit is built, if you format Non-volatile Dynamic RAM you systimaticaly discharge the electrolytic capacitors resulting in there data value being 0, while the common base of the transistors will be +/-5V during a format on RAM
In a Hard Drive
In Hard Drives the same circuit system applies though the capacitors are replaced by +/- B's on the surface of the disks, polarization on the disk indicates data and the design of the disk allows multi-poler polarization (more than one layer) on a single disk.
Interrupting a Low level format on a hardrive can cause magnetic variation that can disrupt the function of the guide magnets at the base of the read head arm.
The chance of this occurring is 1 in 20000 and is more common in hard drives that are under 60 Gb.
Due to Advances in material Sciences most magnetic surfaces in modern hard drives are dipped in a special kind of artificially bio chemically engineered solvent that adds insulating properties to the magnets to prevent damage from certain levels of Tesla.

Each Sector is a group of units that contain similar information.
A Low Level Format just tells the computer that the hard drive is ready for the write procedure. it does not delete data.
 
#4 · (Edited)
"Low level formatting" a drive hasn't been possible for almost 25 years. It refers to the procedure by which a totally blank disc is recorded with servo information, sector ID, sync bits, etc.

This article has a good explanation:

Low-Level Formatting

Low level formatting is the kind of formatting that you do on a blank floppy diskette.

Some low level formatting tools actually just zero-fill your drive, or fill it with a chosen data pattern. You can't damage anything by interrupting the process, but if you interrupt an ATA secure erase procedure, you will leave the drive in a password protected state. That's because a password has to be set before the procedure begins.

See https://ata.wiki.kernel.org/index.php/ATA_Secure_Erase
 
#5 ·
The pattern in binary

00-00-00-00_00-00-00-00_00-00-00-00_00-00-00-00
00-00-00-00_00-00-00-00_00-00-00-00_00-00-00-00
00-00-00-00_00-00-00-00_00-00-00-00_00-00-00-00
00-00-00-00_00-00-00-00_00-00-00-00_00-00-00-00

00-00-00-00
00-00-00-00
00-00-00-00
00-00-00-00

_00-00-00-00_00-00-00-00
00-00-00-00_00-00-00-00_
_00-00-00-00_00-00-00-00
00-00-00-00_00-00-00-00_

These are a few of the patterns used in Low Level Formats and the reason why it is called Zero Filling. Each 0 represents a mono-pole on the disk that has been reversed this is the magnetic version of a capacitor that has been discharged.
 
#6 ·
The ATA-3 standard lists Format Track as a Vendor Specific command. The register values can be defined by HDD manufacturers in their own proprietary way.

"The implementation of the FORMAT TRACK command is vendor specific. It is recommended that system implementations not utilize this command."

http://www.users.on.net/~fzabkar/HDD/LLF/Format_Track_ATA-3.jpg

The FORMAT TRACK command was made obsolete in ATA-4.

Here is the technical manual for the Kalok KL3120 120MB IDE drive manufactured in 1992:

http://archive.hmvh.net/txtfiles/hdd/KL3120.MAN.txt

The following excerpt is essentially saying that the drive ignores any attempt to low level format it and instead fills the data area with zeros. The "sector headers" are written at the factory and cannot be changed in the field.

===============================================================================================
Format Track - (50h) Class 2

The Command block contains the track address. The Sector Count register contains the number of sectors. The drive sets the DRQ bit and waits for the host to fill the sector buffer, when the drive accepts a command. When the sector buffer is full, the drive clears DRQ, sets BSY, and begins to execute the command. If any bits 0-3 are 1, an aborted command sets. If the drive is not already on the desired track, an implied seek executes. The drive clears BSY at the completion of the track
and generates an interrupt. During the Format Track command, zeros write to the user data field bytes. See Figure 2-9. The Format Track command will not change the sector headers. The factory writes the sector headers.

The KL3120 is factory low level formated. The bad sectors are mapped. Users do not need to low level format the KL3120. If you run a low level format program, the drive will not format. The drive will end any format with the data area clear.
===============================================================================================

The drive returns the following information in response to an Identify Device command:

+------------------------------------------------------------+
¦Word Value Description ¦
+------------------------------------------------------------¦
¦Word 00 0A5C A constant 0A5C ¦
¦Word 01 039B Number of fixed cylinders ¦
¦Word 02 0000 Number of removable cylinders ¦
¦Word 03 000F Number of heads ¦
¦Word 04 25B8 Number of unformatted bytes ¦
¦ per physical track ¦
¦Word 05 0238 Number of unformatted bytes per sector ¦
¦Word 06 0011 Number of physical sectors/track ¦
¦Word 07 000F Number of bytes in the inter-sector gaps ¦
¦Word 08 000C Number of bytes in the sync fields ¦

Most of the above words have been obsoleted in later ATA standards, but it can be seen that each sector contains 0x238 unformatted bytes corresponding to 0x200 (= 512 decimal) data bytes plus 0x38 (= 56) overhead bytes. Then there are 15 inter-sector gap bytes and 12 sync bytes. Only the data and ECC bytes are accessible to the user (although this is no longer the case for ECC bytes).

The following document illustrates the overhead bytes (preamble, address, ECC, postamble) in an old 20MB HDD.

http://bitsavers.trailing-edge.com/...ch_Disk_Drive_Product_Specification_Jan83.pdf

http://www.users.on.net/~fzabkar/HDD/LLF/LLF_bytes_read_mode.jpg
 
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