Disk formatting - Wikipedia. Disk formatting is the process of preparing a data storage device such as a hard disk drive, solid- state drive, floppy disk 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 . The earliest disk drives had fixed block sizes (e. The disk subsystems on the IBM System/3. 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 1. HDDs to support variable block size was the IBM 3. Model 9, announced May 1. This is intended to be the permanent foundation of the disk, and is often completed at the factory. Partitioning divides a disk into one or more regions, writing data structures to the disk to indicate the beginning and end of the regions. This level of formatting often includes checking for defective tracks or defective sectors. High- level formatting creates the file system format within a disk partition or a logical volume. This formatting includes the data structures used by the OS to identify the logical drive or partition's contents. This may occur during operating system installation, or when adding a new disk. Disk and distributed file system may specify an optional boot block, and/or various volume and directory information for the operating system. Low- level formatting of floppy disks. Low- level formatting of the floppy disk, normally writes 1. Physical sectors are actually larger than 5. 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. Different low- level formats can be used on the same media; for example, large records can be used to cut down on inter- record gap size. Several freeware, shareware and free software programs (e. GParted, FDFORMAT, NFORMAT and 2. M) allowed considerably more control over formatting, allowing the formatting of high- density 3. With the media, the drive and/or the controller possibly procured from separate vendors, users were often able to perform low- level formatting. Separate procurement also had the potential of incompatibility between the separate components such that the subsystem would not reliably store data. IBM and other mainframe system vendors typically supplied their hard disk drives (or media in the case of removable media HDDs) with a low- level format. Typically this involved subdividing each track on the disk into one or more blocks which would contain the user data and associated control information. Different computers used different block sizes and IBM notably used variable block sizes but the popularity of the IBM PC caused the industry to adopt a standard of 5. Depending upon the system, low- level formatting was generally done by an operating system utility. IBM compatible PCs used the BIOS, which is invoked using the MS- DOS debug program, to transfer control to a routine hidden at different addresses in different BIOSes. At the same time, the industry moved from historical (dumb) bit serial interfaces to modern (intelligent) bit serial interfaces and word serial interfaces wherein the low level format was performed at the factory. Today, an end- user, in most cases, should never perform a low- level formatting of an IDE or ATA hard drive, and in fact it is often not possible to do so on modern hard drives because the formatting is done on a servowriter before the disk is assembled into a drive in the factory. Since much of the low level formatting process can today only be performed at the factory, various drive manufacturers describe reinitialization software as LLF utilities on their web sites. Since users generally have no way to determine the difference between a complete LLF and reinitialization (they simply observe running the software results in a hard disk that must be high- level formatted), both the misinformed user and mixed signals from various drive manufacturers have perpetuated this error. Note: Whatever possible misuse of such terms may exist (search hard drive manufacturers' web sites for all these terms), many sites do make such reinitialization utilities available (possibly as bootable floppy diskette or CD image files), to both overwrite every byte and check for damaged sectors on the hard disk. Reinitialization should include identifying (and sparing out if possible) any sectors which cannot be written to and read back from the drive, correctly. The term has, however, been used by some to refer to only a portion of that process, in which every sector of the drive is written to; usually by writing a specific value to every addressable location on the disk. Traditionally, the physical sectors were initialized with a fill value of 0x. F6 as per the INT 1. Eh's Disk Parameter Table (DPT) during format on IBM compatible machines. This value is also used on the Atari Portfolio. CP/M floppies typically came pre- formatted with a value of 0x. E5. Some modern formatters wipe hard disks with a value of 0x. FF is used on flash disks to reduce wear. The latter value is typically also the default value used on ROM disks (which cannot be reformatted). Some advanced formatting tools allow configuring the fill value. Some operating systems allow the device (or its medium) to appear as multiple devices; i. Formatting Your PC Should Be A Last Resort! Reformatting your Windows computer is usually the absolute last resort when trying to resolve problems and might even be. Wouldn't it be much easier and faster to just back up all your data and then reinstall windows? Of course if you have a lot of software installed, try this. These operating systems support multiple partitions. In current IBM mainframe OSs derived from OS/3. DOS/3. 60, such as z/OS and z/VSE, this is done by the INIT command of the ICKDSF utility. The ICKDSF functions include creating a volume label and writing a Record 0 on every track. Floppy disks are not partitioned; however depending upon the OS they may require volume information in order to be accessed by the OS. Partition editors and ICKDSF today do not handle low level functions for HDDs and optical disc drives such as writing timing marks, and they cannot reinitialize a modern disk that has been degaussed or otherwise lost the factory formatting. High- level formatting. This is a fast operation, and is sometimes referred to as quick formatting. The entire logical drive or partition may optionally be scanned for defects, which may take considerable time. In the case of floppy disks, both high- and low- level formatting are customarily performed in one pass by the disk formatting software. E5. Reformatting is unique to each operating system because what actually is done to existing data varies by OS. The most important aspect of the process is that it frees disk space for use by other data. To actually . Rather than fixing an installation suffering from malfunction or security compromise, it is sometimes judged easier to simply reformat everything and start from scratch. Various colloquialisms exist for this process, such as . The format program usually asks for confirmation beforehand to prevent accidental removal of data, but some versions of DOS have an undocumented /AUTOTEST option; if used, the usual confirmation is skipped and the format begins right away. The WM/Format. C macro virus uses this command to format drive C: as soon as a document is opened. Unconditional format: There is also the /U parameter that performs an unconditional format which under most circumstances overwrites the entire partition. Note however that the /U switch only works reliably with floppy diskettes (see image to the right). Technically because unless /Q is used, floppies are always low level formatted in addition to high- level formatted. Under certain circumstances with hard drive partitions, however, the /U switch merely prevents the creation of unformat information in the partition to be formatted while otherwise leaving the partition's contents entirely intact (still on disk but marked deleted). In such cases, the user's data remain ripe for recovery with specialist tools such as En. Case or disk editors. Reliance upon /U for secure overwriting of hard drive partitions is therefore inadvisable, and purpose- built tools such as DBAN should be considered instead. Overwriting: In Windows Vista and upwards the non- quick format will overwrite as it goes. Not the case in Windows XP and below. Doing so enhances the ability of CHKDSK to recover files. Unix- like operating systems. On Linux (and potentially other systems as well) mkfs is typically a wrapper around filesystem- specific commands which have the name mkfs. Examples include GNU Parted (and its various GUI frontends such as GParted and the KDE Partition Manager) and the Disk Utility application on Mac OS X. Recovery of data from a formatted disk. Instead, the area on the disk containing the data is merely marked as available, and retains the old data until it is overwritten. If the disk is formatted with a different file system than the one which previously existed on the partition, some data may be overwritten that wouldn't be if the same file system had been used. However, under some file systems (e. NTFS, but not FAT), the file indexes (such as $MFTs under NTFS, inodes under ext. And if the partition size is increased, even FAT file systems will overwrite more data at the beginning of that new partition. From the perspective of preventing the recovery of sensitive data through recovery tools, the data must either be completely overwritten (every sector) with random data before the format, or the format program itself must perform this overwriting, as the DOSFORMAT command did with floppy diskettes, filling every data sector with the format filler byte value (typically 0x. F6). However, there are applications and tools, especially used in forensic information technology, that can recover data that has been conventionally erased. In order to avoid the recovery of sensitive data, governmental organization or big companies use information destruction methods like the Gutmann method.
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