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Why is the total number of hard disk sectors shown in fdisk not the same as theoretical calculation?
Disk problems prevent me from booting, or set the disk to read-only. How do I fix the disk?Debian Wheezy live - gparted, dmsg, fdisk etc. do not detect local hard drive but it is shown during installationExpanding root partition CentOS 6 With using fdiskHow to extend logical & extended partition with fdiskExtend partition using LVMHow to ensure the same speed of hard disks among cluster machines?Hard disk shows '193' bad sectors and makes a repetitive clicking noiseI have a dedicated with 2 SSDs, how to I group them to behave as 1?Merge unallocated hard disk spaceHow to calculate partition Start End Sector?
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When we use fdisk to check a hard disk, it would show something like:
Disk /dev/sda/: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
But when we multiply 255 x 63 x 2610, the number is 41929650, slightly less than the total no. of sectors shown above. Why?
hard-disk fdisk
asked 8 hours ago
GreenPenguinGreenPenguin
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When we use fdisk to check a hard disk, it would show something like:
Disk /dev/sda/: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
But when we multiply 255 x 63 x 2610, the number is 41929650, slightly less than the total no. of sectors shown above. Why?
hard-disk fdisk
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
When we use fdisk to check a hard disk, it would show something like:
Disk /dev/sda/: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
But when we multiply 255 x 63 x 2610, the number is 41929650, slightly less than the total no. of sectors shown above. Why?
hard-disk fdisk
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
When we use fdisk to check a hard disk, it would show something like:
Disk /dev/sda/: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders, total 41943040 sectors
But when we multiply 255 x 63 x 2610, the number is 41929650, slightly less than the total no. of sectors shown above. Why?
hard-disk fdisk
hard-disk fdisk
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
asked 8 hours ago
GreenPenguinGreenPenguin
283 bronze badges
283 bronze badges
New contributor
GreenPenguin is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
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1 Answer
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The head, cylinder, sector numbers are displayed for historical purposes only, and for use by some really old software. Logical Block Addressing is used to address disks today. The geometry of modern disks typically have a variable number of sectors, outer tracks have more sectors than inner tracks.
Various interfaces have maximum values of 255 heads, 63 sectors/track, so to be able to express the CHS values for a large disk, these are set to their respective maximum values and the number of cylinders is rounded down to the nearest integer value giving an approximate value of the number of total sectors on the disk. The real number of sectors is typically different, as you have seen. The actual geometry of the disk is not even close to the CHS values; probably no disk ever manufactured has 255 heads, for example.
answered 7 hours ago
Johan MyréenJohan Myréen
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1 Answer
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The head, cylinder, sector numbers are displayed for historical purposes only, and for use by some really old software. Logical Block Addressing is used to address disks today. The geometry of modern disks typically have a variable number of sectors, outer tracks have more sectors than inner tracks.
Various interfaces have maximum values of 255 heads, 63 sectors/track, so to be able to express the CHS values for a large disk, these are set to their respective maximum values and the number of cylinders is rounded down to the nearest integer value giving an approximate value of the number of total sectors on the disk. The real number of sectors is typically different, as you have seen. The actual geometry of the disk is not even close to the CHS values; probably no disk ever manufactured has 255 heads, for example.
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
add a comment |
The head, cylinder, sector numbers are displayed for historical purposes only, and for use by some really old software. Logical Block Addressing is used to address disks today. The geometry of modern disks typically have a variable number of sectors, outer tracks have more sectors than inner tracks.
Various interfaces have maximum values of 255 heads, 63 sectors/track, so to be able to express the CHS values for a large disk, these are set to their respective maximum values and the number of cylinders is rounded down to the nearest integer value giving an approximate value of the number of total sectors on the disk. The real number of sectors is typically different, as you have seen. The actual geometry of the disk is not even close to the CHS values; probably no disk ever manufactured has 255 heads, for example.
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
add a comment |
The head, cylinder, sector numbers are displayed for historical purposes only, and for use by some really old software. Logical Block Addressing is used to address disks today. The geometry of modern disks typically have a variable number of sectors, outer tracks have more sectors than inner tracks.
Various interfaces have maximum values of 255 heads, 63 sectors/track, so to be able to express the CHS values for a large disk, these are set to their respective maximum values and the number of cylinders is rounded down to the nearest integer value giving an approximate value of the number of total sectors on the disk. The real number of sectors is typically different, as you have seen. The actual geometry of the disk is not even close to the CHS values; probably no disk ever manufactured has 255 heads, for example.
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
The head, cylinder, sector numbers are displayed for historical purposes only, and for use by some really old software. Logical Block Addressing is used to address disks today. The geometry of modern disks typically have a variable number of sectors, outer tracks have more sectors than inner tracks.
Various interfaces have maximum values of 255 heads, 63 sectors/track, so to be able to express the CHS values for a large disk, these are set to their respective maximum values and the number of cylinders is rounded down to the nearest integer value giving an approximate value of the number of total sectors on the disk. The real number of sectors is typically different, as you have seen. The actual geometry of the disk is not even close to the CHS values; probably no disk ever manufactured has 255 heads, for example.
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
answered 7 hours ago
Johan MyréenJohan Myréen
8,4241 gold badge17 silver badges26 bronze badges
8,4241 gold badge17 silver badges26 bronze badges
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