Re: Low Level Format Zero Fill
Bubba Lual
Actually the term "low level" is a bit of a misnomer. The low-level process first used years ago in MFM hard drives bears little resemblance to what we now call a "low-level format" for today's SATA and ATA (IDE) drives. The only safe method of initializing all the data on a Seagate device is the zero fill erase option in SeaTools for DOS. This is a simple process of writing all zeros (0's) to the entire hard disk drive.
By design, modern disc drives maintain spare sectors for reallocation purposes. Usually, sectors become difficult to read long before they become impossible to read. In this situation the actual data bytes in the sector are preserved and transferred to the new spare during a sector reallocation. Similarly, when a disc drive writes data (like a zero fill erase procedure) and encounters a problem, the drive firmware retires the problem sector and activates a replacement before giving successful write status.
SeaTools for DOS can be downloaded from the SeaTools homepage. It includes three Erase (Zero Fill) options. Zero Fill writes zeros in each data sector for the complete capacity of the drive and cleans up most defects.
The download routine for SeaTools for DOS creates a bootable CD or floppy diskette. Boot from the CD media or diskette to start SeaTools for DOS. After startup, it is a good idea to test your drive. The Basic Short Test takes less than a minute to complete. The Basic Long Test can take several hours to complete, depending on the capacity of the drive. When you are ready to erase the drive, select the drive you want to erase. Then select one of the three zero fill Erase functions.
Erase Track ZERO: Erases just the first 63 sectors on the drive which takes less than a second to complete. This procedure removes the Master Boot Record (MBR) and Partition Table. This will cause the drive to look "empty" to a new installation of the operating system.
Timed Erase: Erases sectors for various time limits up to 5 minutes. These options will overwrite the sectors at the beginning of the drive where the majority of the static operating system files reside.
Full Erase: Erases every data sector on the drive and takes a long time to complete. This procedure can easily take several hours to complete. The advantage of this option is to discover and reallocate any defective (hard to read) sectors to good spares. This option comes closest in concept to the original idea of a low level format.
Note that a low-level format is a more thorough process than a regular format and may take significantly longer to complete. However, it should effectively reset the drive and allow you to access the full capacity again.
Historical meaning of the term Low Level Format doesn't apply to memory chips (and hence to an SSD) at all. That is because in magnetic disks (and tapes) Low Level Format is used to place discrete marks onto the analog surface. There are no analog elements in memory chips.
Zero-filling an SSD which is not TRIM-capable is a trick used to improve write performance. SSD can write data quickly only to a blank (zero-filled) block. But if there are no blank blocks, then it is necessary to erase some blocks before new data can be written.The process of erasing takes a long time. The need to erase blocks decreases performance of an SSD without TRIM because of such an SSD cannot erase blocks in advance. Therefore, zero-filling applied to an SSD without TRIM speeds write operations up for a while.
At the factory some sectors are reserved to a special pool to compensate for possible surface defects, both manufacturing and operational. If a sector becomes defective for whatever reason, one of the reserved sectors will be used instead. This is called "reallocation". Bad sector is a sector on which write operation fails. Since Low Level Format requires that each sector should be overwritten with zeroes, it helps detect bad sectors and therefore forces a hard disk to reallocate them.
It is needed to use Low Level Format for reallocation if you are going to work with a second-hand hard drive. In this case, in addition to removing other people's data, you force a hard disk to reallocate bad sectors, if there are any.
This freeware HDD Low Level Format utility can erase, Low-Level Format and re-certify a SATA, IDE, SAS, SCSI, SSD hard disk drive. Will also work with any USB and FIREWIRE external drive enclosures as well as SD, MMC, MemoryStick and CompactFlash...
Catalogue Professional Hardware-Software Solutions for Data Recovery & Digital Forensics. ACE Lab, the Czech Republic - These are pretty well regarded as far as I can tell and can do cool things with firmware and stuff
Yup, and IIRC some of the proprietary bootable diagnostics tools (SeaTools, Maxtor PowerMax are the ones that come to mind) could run routines in the drive firmware back in the old days, but that was before even SATA existed.
Secure erase overwrites all user data areas with binary zeroes. Enhanced secure erase writes predetermined data patterns (set by the manufacturer) to all user data areas, including sectors that are no longer in use due to reallocation.
If you can describe the ATA bus commands being issued over SATA that are initiating a low-level format then I would love to be proven wrong. The linux hdparm llformat is just a poorly named secure erase implementation.
Digital files on a memory card or hard drive are stored as 1s and 0s. A header is created telling the camera or computer where the photo files are stored on the hard drive or card, where the file starts and stops. If the headers are deleted, the camera or computer does not see a photo file there and can write over that space with a new photo and creates a new header.
The Format removes the headers, but the 1s and 0s of the photo are still there, just no header saying where they are. Some file recovery software could still rescue these files with no headers by scanning the drive and figuring out where files start and stop and create new headers.
There are some cases where you may want to do a Low Level Format, if you had a memory card that may have been low level formatted with some strange format that the camera can not recognize, if the camera does no recognize the card try a Low Level Format.
Disk formatting is the process of preparing a data storage device such as a hard disk drive, solid-state drive, floppy disk, memory card or USB flash drive for initial use. In some cases, the formatting operation may also create one or more new file systems. The first part of the formatting process that performs basic medium preparation is often referred to as "low-level formatting".[1] Partitioning is the common term for the second part of the process, dividing the device into several sub-devices and, in some cases, writing information to the device allowing an operating system to be booted from it.[1][2] The third part of the process, usually termed "high-level formatting" most often refers to the process of generating a new file system.[1] In some operating systems all or parts of these three processes can be combined or repeated at different levels[a] and the term "format" is understood to mean an operation in which a new disk medium is fully prepared to store files. Some formatting utilities allow distinguishing between a quick format, which does not erase all existing data and a long option that does erase all existing data.
As a general rule,[b] formatting a disk by default leaves most if not all existing data on the disk medium; some or most of which might be recoverable with privileged[c] or special tools.[6] Special tools can remove user data by a single overwrite of all files and free space.[7]
A block, a contiguous number of bytes, is the minimum unit of storage that is read from and written to a disk by a disk driver. The earliest disk drives had fixed block sizes (e.g. the IBM 350 disk storage unit (of the late 1950s) block size was 100 six-bit characters) but starting with the 1301[8] IBM marketed subsystems that featured variable block sizes: a particular track could have blocks of different sizes. The disk subsystems and other direct access storage devices on the IBM System/360 expanded this concept in the form of Count Key Data (CKD) and later Extended Count Key Data (ECKD); however the use of variable block size in HDDs fell out of use in the 1990s; one of the last HDDs to support variable block size was the IBM 3390 Model 9, announced May 1993.[9]
Modern hard disk drives, such as Serial attached SCSI (SAS)[d] and Serial ATA (SATA)[10] drives, appear at their interfaces as a contiguous set of fixed-size blocks; for many years 512 bytes long but beginning in 2009 and accelerating through 2011, all major hard disk drive manufacturers began releasing hard disk drive platforms using the Advanced Format of 4096 byte logical blocks.[11][12]
Floppy disks generally only used fixed block sizes but these sizes were a function of the host's OS and its interaction with its controller so that a particular type of media (e.g., 5-inch DSDD) would have different block sizes depending upon the host OS and controller.
Physical sectors are actually larger than 512 bytes, as in addition to the 512 byte data field they include a sector identifier field, CRC bytes (in some cases error correction bytes) and gaps between the fields. These additional bytes are not normally included in the quoted figure for overall storage capacity of the disk.
Several freeware, shareware and free software programs (e.g. GParted, FDFORMAT, NFORMAT, VGA-Copy and 2M) allowed considerably more control over formatting, allowing the formatting of high-density 3.5" disks with a capacity up to 2 MB.
After establishing the structure of tracks, a formatter also needs to fill the entire floppy and look for bad sectors. Traditionally, the physical sectors were initialized with a fill value of 0xF6 as per the INT 1Eh's Disk Parameter Table (DPT) during format on IBM compatible machines. This value is also used on the Atari Portfolio. CP/M 8-inch floppies typically came pre-formatted with a value of 0xE5,[15] and by way of Digital Research this value was also used on Atari ST and some Amstrad formatted floppies.[f] Amstrad otherwise used 0xF4 as a fill value.
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