Editing Disk formatting (section)

=== High-level formatting ===

High-level formatting is the process of setting up an empty file system on a disk partition or a [[logical volume]] and for PCs, installing a [[boot sector]].<ref name="Tanenbaum" /> This is often a fast operation, and is sometimes referred to as ''quick formatting''.

Formatting an entire logical drive or partition may optionally scan 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. Eight-inch floppies typically came low-level formatted and were filled with a format filler value of <code>0xE5</code>.<ref name="Schulman_1994_Undocumented-DOS"/><ref group="lower-alpha" name="NB_Magic_E5"/> Since the 1990s, most 5.25-inch and 3.5-inch floppies have been shipped pre-formatted from the factory as DOS [[FAT12]] floppies.

In current IBM mainframe operating systems derived from [[OS/360]] and [[DOS/360]], such as [[z/OS]] and [[z/VSE]], formatting of drives is done by the INIT command of the [[ICKDSF]] utility.<ref>{{Cite web |url=http://publibz.boulder.ibm.com/epubs/pdf/ick4020f.pdf |title=Device Support Facilities User's Guide and Reference |access-date=2010-12-27 |archive-date=2021-12-09 |archive-url=https://web.archive.org/web/20211209100904/http://publibz.boulder.ibm.com/epubs/pdf/ick4020f.pdf |url-status=dead }}</ref> These OSs support only a single partition per device, called a volume. The ICKDSF functions include writing a Record 0 on every track, writing [[Initial Program Load|IPL]] text, creating a volume label, creating a [[Volume Table of Contents]] (VTOC) and, optionally, creating a VTOC index (VTOCIX); high level formatting may also be done as part of allocating a file, by a utility specific to a file system or, in some older access methods, on the fly as new data are written. In z/OS Unix System Services, there are three distinct levels of high-level formatting:
*Initializing a volume with ICKDSF
*Initializing a [[VSAM]] Linear Data Set (LDS) as part of allocating it on the volume with Access Method Services (IDCAMS) DEFINE
*Initializing a [[zFS (z/OS file system)|zFS]] aggregate in the LDS using ioeagfmt.

In IBM operating systems derived from [[CP-67]], formatting a volume initializes track 0 and a dummy VTOC. Guest operating systems are responsible for formatting [[minidisk (VM)|minidisks]]; the CMS FORMAT command formats a [[CMS file system]] on a CMS minidisk.