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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 ...
Size Density Sides Tracks tpi bpi Sectoring Coercivity Unformatted capacity per side 2 inch Video Floppy: 52 256 >800 kB or 50 fields of analog video [1] 2 inch LT-1: double 80 245 2 1 ⁄ 2 inch: Single 16 [2] [3] 48 [2] 64 kB 3 inch QuickDisk: 3.25 inch single 1 80 [4] 140 4,625 250 kB double 9,250 500 kB 3 1 ⁄ 2 inch: Single 2: 40 [5] 67.5 ...
If the actual size of the disk exceeds the maximum partition size representable using the legacy 32-bit LBA entries in the MBR partition table, the recorded size of this partition is clipped at the maximum, thereby ignoring the rest of the disk. This amounts to a maximum reported size of 2 TiB, assuming a disk with 512 bytes per sector (see 512e).
Variables included the size of media (nominal 8-inch, 5 + 1 ⁄ 4-inch, 3 + 1 ⁄ 2-inch and others), encoding of data on the media (FM, MFM, M²FM, GCR), the number of disk tracks, one or two sides, the number of sectors in each track, and hard- or soft-sectoring. Even media that was physically interchangeable between two systems might not ...
The sector size and sectors per track depend on how the disk is initialized. For example on the GEC 4000 series minicomputers a configuration of 34 sectors of 512 data bytes each per track is used. SMD disk packs (as the Storage Module itself was most commonly called) required head alignment to assure interchangeability of media between drives.
Drives may slot into a drive bay of the corresponding size. Compared to flash drives in same form factor, maximum rotating disk drive capacity is much smaller, [citation needed] with 100 TB available in 2018, [1] and 32 TB for 2.5-inch. [2] The disk drive size, such as 3.5-inch, is usually refers to the diameter of the disk platters.
The unformatted capacity of a floppy disk does not include the sector and track headings of a formatted disk; the difference in storage between them depends on the drive's application. Floppy disk drive and media manufacturers specify the unformatted capacity (for example, 2 MB for a standard 3½-inch HD floppy).
The partition type (or partition ID) in a partition's entry in the partition table inside a master boot record (MBR) is a byte value intended to specify the file system the partition contains or to flag special access methods used to access these partitions (e.g. special CHS mappings, LBA access, logical mapped geometries, special driver access, hidden partitions, secured or encrypted file ...