Since the invention of the floppy disk drive, various standardized form factors have been used in computing systems. Standardized form factors and interface allow a variety of peripherals and upgrades thereto with no impact to the physical size of a computer system. 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 [update], [1] and 32 TB for 2.5-inch. [2]
Form factor (inch) |
Status | Dimensions (Dimension in inches unless otherwise noted) |
Largest capacity | Platters (max.) | Capacity per platter (GB) | ||
---|---|---|---|---|---|---|---|
Length | Width | Height | |||||
3.5 | Current | 5.75 | 4.0 | 0.72 [3] or 26.11 mm [4] or 19.99 mm [5] | 30 TB (November 2023) [6] | 10 [7] (June 2022) [8] | 2.6TB |
2.5 | Current | 4.0 | 2.75 | 5,
[9] 7, 9.5,
[a] 12.5, 15 or 19
[10] (all mm) |
5 TB [11] (October 2016, no improvement since.) | 5 [12] | 1,000 |
1.8 | Obsolete | 78.5 mm, [b] 71 mm [c] | 54 mm | 5 mm [13] or 8 mm | 320 GB [14] (2009) | 2 | 220 [15] |
8 | Obsolete | 14.5 | 9.5 | 4.625 | 2.0 GB (1989) [16] [17] | Unknown. Minimum, 12 |
Unknown. Minimum, 0.16 |
5.25 ( FH) | Obsolete | 8.0 | 5.75 | 3.25 | 47 GB [18] (1998) | 14 | 3.36 |
5.25 ( HH) | Obsolete | 8.0 | 5.75 | 1.625 | 19.3 GB [19] (1998) | 4 [d] | 4.83 |
1.3 | Obsolete | 50.8 mm [20] | 36.5 mm [20] | 10.5 mm [20] | 40 GB [21] (2007) | 1 | 40 |
1 (CFII/ZIF/IDE-Flex, " Microdrive") | Obsolete | 42.8 mm | 36.4 mm | 5 mm | 20 GB (2006) | 1 | 20 |
0.85 | Obsolete | 32 mm | 24 mm | 5 mm | 8 GB [22] [23] (2004) | 1 | 8 |
IBM's first hard drive, the IBM 350, used a stack of fifty 24-inch platters and was of a size comparable to two large refrigerators. In 1962, IBM introduced its model 1311 disk, which used six 14-inch (nominal size) platters in a removable pack and was roughly the size of a washing machine. This became a standard platter size and drive form-factor for many years, used also by other manufacturers. The IBM 2314 used platters of the same size in an eleven-high pack and introduced the "drive in a drawer" layout, although the "drawer" was not the complete drive.
Later drives were designed to fit entirely into a chassis that would mount in a 19-inch rack. Digital's RK05 and RL01 were early examples using single 14-inch platters in removable packs, the entire drive fitting in a 10.5-inch-high rack space (six rack units). In the mid-to-late 1980s the similarly sized Fujitsu Eagle, which used (coincidentally) 10.5-inch platters, was a popular product.
Such large platters were never used with microprocessor-based systems. With increasing sales of microcomputers having built in floppy-disk drives (FDDs), HDDs that would fit to the FDD mountings became desirable. Thus HDD Form factors, initially followed those of 8-inch, 5.25-inch, and 3.5-inch floppy disk drives. Because there were no smaller floppy disk drives, smaller HDD form factors developed from product offerings or industry standards.
As of 2023 [update], 2.5-inch and 3.5-inch hard disks are the most popular sizes.
By 2009, all manufacturers had discontinued the development of new products for the 1.3-inch, 1-inch and 0.85-inch form factors due to falling prices of flash memory, which has no moving parts.[ citation needed]
While these sizes are customarily described by an approximately correct figure in inches, actual sizes have long been specified in millimeters. The older 3.5-inch form factor uses UNC threads, while 2.5-inch drives use metric M3 threads.
{{
cite web}}
: CS1 maint: archived copy as title (
link)
Since the invention of the floppy disk drive, various standardized form factors have been used in computing systems. Standardized form factors and interface allow a variety of peripherals and upgrades thereto with no impact to the physical size of a computer system. 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 [update], [1] and 32 TB for 2.5-inch. [2]
Form factor (inch) |
Status | Dimensions (Dimension in inches unless otherwise noted) |
Largest capacity | Platters (max.) | Capacity per platter (GB) | ||
---|---|---|---|---|---|---|---|
Length | Width | Height | |||||
3.5 | Current | 5.75 | 4.0 | 0.72 [3] or 26.11 mm [4] or 19.99 mm [5] | 30 TB (November 2023) [6] | 10 [7] (June 2022) [8] | 2.6TB |
2.5 | Current | 4.0 | 2.75 | 5,
[9] 7, 9.5,
[a] 12.5, 15 or 19
[10] (all mm) |
5 TB [11] (October 2016, no improvement since.) | 5 [12] | 1,000 |
1.8 | Obsolete | 78.5 mm, [b] 71 mm [c] | 54 mm | 5 mm [13] or 8 mm | 320 GB [14] (2009) | 2 | 220 [15] |
8 | Obsolete | 14.5 | 9.5 | 4.625 | 2.0 GB (1989) [16] [17] | Unknown. Minimum, 12 |
Unknown. Minimum, 0.16 |
5.25 ( FH) | Obsolete | 8.0 | 5.75 | 3.25 | 47 GB [18] (1998) | 14 | 3.36 |
5.25 ( HH) | Obsolete | 8.0 | 5.75 | 1.625 | 19.3 GB [19] (1998) | 4 [d] | 4.83 |
1.3 | Obsolete | 50.8 mm [20] | 36.5 mm [20] | 10.5 mm [20] | 40 GB [21] (2007) | 1 | 40 |
1 (CFII/ZIF/IDE-Flex, " Microdrive") | Obsolete | 42.8 mm | 36.4 mm | 5 mm | 20 GB (2006) | 1 | 20 |
0.85 | Obsolete | 32 mm | 24 mm | 5 mm | 8 GB [22] [23] (2004) | 1 | 8 |
IBM's first hard drive, the IBM 350, used a stack of fifty 24-inch platters and was of a size comparable to two large refrigerators. In 1962, IBM introduced its model 1311 disk, which used six 14-inch (nominal size) platters in a removable pack and was roughly the size of a washing machine. This became a standard platter size and drive form-factor for many years, used also by other manufacturers. The IBM 2314 used platters of the same size in an eleven-high pack and introduced the "drive in a drawer" layout, although the "drawer" was not the complete drive.
Later drives were designed to fit entirely into a chassis that would mount in a 19-inch rack. Digital's RK05 and RL01 were early examples using single 14-inch platters in removable packs, the entire drive fitting in a 10.5-inch-high rack space (six rack units). In the mid-to-late 1980s the similarly sized Fujitsu Eagle, which used (coincidentally) 10.5-inch platters, was a popular product.
Such large platters were never used with microprocessor-based systems. With increasing sales of microcomputers having built in floppy-disk drives (FDDs), HDDs that would fit to the FDD mountings became desirable. Thus HDD Form factors, initially followed those of 8-inch, 5.25-inch, and 3.5-inch floppy disk drives. Because there were no smaller floppy disk drives, smaller HDD form factors developed from product offerings or industry standards.
As of 2023 [update], 2.5-inch and 3.5-inch hard disks are the most popular sizes.
By 2009, all manufacturers had discontinued the development of new products for the 1.3-inch, 1-inch and 0.85-inch form factors due to falling prices of flash memory, which has no moving parts.[ citation needed]
While these sizes are customarily described by an approximately correct figure in inches, actual sizes have long been specified in millimeters. The older 3.5-inch form factor uses UNC threads, while 2.5-inch drives use metric M3 threads.
{{
cite web}}
: CS1 maint: archived copy as title (
link)