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![]() | The contents of the Cylinder (disk drive) page were merged into Cylinder-head-sector. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. |
The lines: "Most modern drives have a surplus space that doesn't make a cylinder boundary. Each partition should always start and end at a cylinder boundary. Only some of the most modern OSs may disregard this rule, but this can cause some compatibility problems, especially if the user wants to boots up to more than one OS on the same drive."
...seem a bit out of place, because there's a section on IDE drives immediately following.
It is talking about IDE drives, when it says "most modern drives," ...right?
I don't understand about the "surplus space" - doesn't Zone Bit Recording take care of that?
Or is it that, even under ZBR, there's a little bit of extra space on each cylinder?
Doesn't ZBR make the cylinder completely transparent, and you're basically just addressing sectors? How would a program know where the cylinder boundary is, since each cylinder has a different number of sectors? LionKimbro
"Only some of the most modern operating systems"??? Hasn't Linux always (i.e., for 15 years, as of 2006) allowed any kind of partition boundaries?
There is no trusted source for this statement:
"For operating systems such as Microsoft DOS or Windows (before Vista), each partition must start and end at a cylinder boundary."
My personal experience: at least since Win98SE theese non cylinder boundary partitions and partition tables can be read, although their partitioning programs don`t create non cylinder boundary partitions. Only Symantec/Notrton Partition Magic 8.x won`t handle such partitions. Non of you ever had mixed linux and windows installations on a single harddrive? Nerver used GParted for creating windows partitions? 89.58.155.42 ( talk) 18:58, 2 April 2008 (UTC)
I'm aware of drives (the current 5200RPM Hitachi 2.5" drives) some of which have an odd number of heads (the 20GB drive has one platter with one head, the 60GB drive has two platters with three heads). I suspect that this is rather common.
I'm sorry I can't log in at the moment but ... The above may be true for the drives that were made in the 1980s, for the original IBM PC. The values now, make no particular sense that is applicable to all drives from every drive maker. The manufacturer is responsible for making the presentation of the physical disk medium to a place where someone writing operating system level code, can reliably address it. This requires some cooperation from the BIOS folks who have traditionally been responsible for reporting the correct disk size, to the OS. As of the Vista version of the Windows OS, Windows will began to assume some of the responsibility for obtaining information from the BIOS. (There was a time when no BIOS had a setting that pertains to a PnP OS). Linux has ignored BIOS settings for quite some time. These things aside, it is clear that some contributors do not even know. A track and a cylinder are definitely /not/ the same thing but I just saw text that says they are. In addition, the drawing of the platters for this entry should show the platter stack from an oblique angle so that the drawing is not misinterpreted to say the same thing. To add to this, since a floppy is always a single platter, the number of cylinders is the same as the number of tracks (as the definition I read and changed stated) if the platter can hold data on one side, only. Probably the only thing that persists is that there is one head per writable side of each platter. The point to make clear is that the heads are not part of the disks, or of the disk stack, although they are part of the drive. —Preceding unsigned comment added by 67.40.35.153 ( talk) 04:35, 20 November 2008 (UTC)
This article might want to mention something about how the cylinders, heads and sectors are counted. I was just reading about the classical PC (DOS) partition table and how the first sector is located at cylinder 0, head 0, sector 1 (CHS 001). This is where the master boot record (MBR) is stored. However, the address CHS 000 seems to be illegal. Are all CHS addresses ending in 0 invalid, or just this first one? -- Jwinius 15:49, 19 April 2007 (UTC)
1. Cylinder: 0 - 1023 (for a maximum total of 1024). 2. Head: 0 - 254 (for a maximum total of 255). 3. Sector: 1 - 63 (for a maximum total of 63).
As one proceeds through LBA counts of 0, 1, 2, etc., the following are a few corresponding CHS tuples that may be very helpful in understanding their relationship (for drives that have 63 sectors per head):
LBA 0 = CHS 0,0,1 LBA 62 = CHS 0,0,63 LBA 63 = CHS 0,1,1
Likewise, for drives that have a pseudo-geometry of 255 heads per cylinder (which may be determined by your operating system these days; e.g., many Linux installs are based on only 16 heads/cylinder, whereas the same physical disk might have 255 heads/cylinder under a Windows OS), the following would be true:
LBA 16,002 = CHS 0,254,1 LBA 16,064 = CHS 0,254,63 LBA 16,065 = CHS 1,0,1
And the maximum LBA sector that CHS can provide a valid corresponding tuple for is at: CHS 1023,254,63 which is equivalent to an LBA of 16,450,559 for 16,450,560 sectors, total; which was passed when hard disks began to exceed a size of 8,422,686,720 bytes, (about 8.42 GB; or 7.84 GiB). Daniel B. Sedory 22:31, 10 June 2007 (UTC)
NOTE: All of the above and more has been added to the article since Jwinius asked about it. Daniel B. Sedory 27 November 2008.
Just a quick note here to mention that I'll be slowly merging the small amount of material at Disk sector into various sections here. Any comments would be appreciated. Daniel B. Sedory 19:27, 7 October 2007 (UTC)
When I started editing this article, its use of the term 'Sector' in CHS (Cylinder,Head,Sector) as the geometrical sector (or slice) common to mathematics, etc. was (and still is) rather compelling. So, I kept that usage as best I could even when adding content to the article Disk sector; based upon what I'd read here and in Circular sector. As a reflection on this topic, I'm asking (musing) whether or not block should continue being used here as the smallest 'chunk of data' one can 'read from/write to' an HDD through its interface (controller card), and how best to point out that 'Sectors' in CHS notation doesn't necessarily mean the same thing as Sectors in HDD capacity calculations. I'm still thinking this through but wanted to present some data and ideas concerning this.
One possible reason the use of "block" was replaced by the now more common term "sector," may be that 'block' was viewed as being somewhat artificially inserted into formulas for computing a disk's capacity: We know many of these formulas use the pseudo drive values of: "63 sectors" and "255 heads," but what units are associated with them? If we use a formula often found in simplified web presentations: S sectors/head x H heads/cylinder x C cylinders
, we can't help but notice both the 'head' and 'cylinder' units cancel each other out, giving us S x H x C sectors
; apparently keeping all the units straight. But do these units actually correspond with reality?
Did the change from the real number of physical 'sectors' and drive 'heads' (perhaps when Zone bit recording became standard on all new HDDs?) signal the rise of 'sectors' vs. 'blocks'?
The formulas presented in this article arrive at drive capacity from some physically real units that still apply to floppy diskettes: S SectorSlices/Side x H Sides x C Cylinders = S x H x C (SectorSlices x Cylinders)
(where Side is equivalent to 'head'). The only way to resolve this result into a single unit is by defining another term as equivalent to "SectorSlices x Cylinders"; which this article does by stating:
blocksPerPlatterSide = (cylindersPerPlatter)*(SectorsPerPlatter)
which is directly related to its definition of block as: The intersection of a cylinder and a sector (SectorSlices x Cylinders). So, what's wrong with the first formula I presented here from popular web sites? I'll have to leave that for another time! Daniel B. Sedory 10:34, 17 June 2007 (UTC)
Αcording to the book "Data Management Systems" 3rd edition, by Ramakrishnan and Gehrke, (pages 306-307): "Each track is divided into arcs, called sectors [...]. The size of a disk block can be set when the disk is initialized as a multiple of the sector size." This is a much different definition than the one given here. What are the sources for the definition of sector and block here? —Preceding unsigned comment added by 195.148.60.152 ( talk) 12:56, 27 October 2008 (UTC)
The article says in section “ Cylinders” that 255 * 63 is 16,064. At least this is the way I understood the wording. Actually, 255 * 63 is 16,065. So, where’s the mistake in the article? If there is a special reason to use 16,064 sectors per cylinder, more explanatory text around that should be added. If the number is wrong, it just needs to be changed.
Please merge the Cylinder (disk drive) stub into this article. – 82.113.99.139 ( talk) 14:18, 30 July 2011 (UTC)
Hi, Ocdex trimmed two occurences of "The in essence" something to "In essence" something in the Heads section, is that as it should be? I undid my "fix" of the 1st case when the 2nd case convinced me that this was an intentional modification. – 89.204.153.138 ( talk) 03:49, 15 September 2011 (UTC)
Is the figure depicting a disk sector accurate? If one read this with the information in the article I'm having a hard time adapting this into a physical reality.
Using the figure:
+-----+ | | Track 1 +-----+
+---------------------------+ | | Track 32 +---------------------------+
Are those two both supposed to hold the same amount of bits? E.g. 512*8?
Are they even larger then 512*8 due to the fact of what is described under disk sectors: "In disk drives, each physical sector is made up of three basic parts, the sector header, the data area and the error-correcting code (ECC)."
[1]
Disk sector: "Thus, the disk sector (Figure 1, item C) refers to the intersection of a track and geometrical sector."
-- Warumwarum ( talk) 11:01, 9 October 2013 (UTC)
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This article should clarify that "allocation unit", "block", and "cluster" are all terms referring to the same concept on different platforms. And if I'm missing some subtle difference between some of these terms, that should probably also be made clear. Currently different paragraphs use one or two terms and it's not always clear whether or to what extent they are interchangeable. It might be worth noting that some historical systems even used other terms. The term in the TRS-80 world was "granule" and one OS on that platform, NEWDOS/80 even introduced another level of abstraction termed the "lump". — Hippietrail ( talk) 02:59, 13 June 2020 (UTC)
It's a little early in the 2000s to be commenting on the "late 2000s" already. Can this be re-worded? I'm really not sure which time period is being referred to:
but many tools for manipulating the master boot record (MBR) partition table still aligned partitions to cylinder boundaries; thus, artifacts of CHS addressing were still seen in partitioning software by the late 2000s
24.196.190.186 (
talk)
13:24, 26 August 2022 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||
|
![]() | The contents of the Cylinder (disk drive) page were merged into Cylinder-head-sector. For the contribution history and old versions of the redirected page, please see its history; for the discussion at that location, see its talk page. |
The lines: "Most modern drives have a surplus space that doesn't make a cylinder boundary. Each partition should always start and end at a cylinder boundary. Only some of the most modern OSs may disregard this rule, but this can cause some compatibility problems, especially if the user wants to boots up to more than one OS on the same drive."
...seem a bit out of place, because there's a section on IDE drives immediately following.
It is talking about IDE drives, when it says "most modern drives," ...right?
I don't understand about the "surplus space" - doesn't Zone Bit Recording take care of that?
Or is it that, even under ZBR, there's a little bit of extra space on each cylinder?
Doesn't ZBR make the cylinder completely transparent, and you're basically just addressing sectors? How would a program know where the cylinder boundary is, since each cylinder has a different number of sectors? LionKimbro
"Only some of the most modern operating systems"??? Hasn't Linux always (i.e., for 15 years, as of 2006) allowed any kind of partition boundaries?
There is no trusted source for this statement:
"For operating systems such as Microsoft DOS or Windows (before Vista), each partition must start and end at a cylinder boundary."
My personal experience: at least since Win98SE theese non cylinder boundary partitions and partition tables can be read, although their partitioning programs don`t create non cylinder boundary partitions. Only Symantec/Notrton Partition Magic 8.x won`t handle such partitions. Non of you ever had mixed linux and windows installations on a single harddrive? Nerver used GParted for creating windows partitions? 89.58.155.42 ( talk) 18:58, 2 April 2008 (UTC)
I'm aware of drives (the current 5200RPM Hitachi 2.5" drives) some of which have an odd number of heads (the 20GB drive has one platter with one head, the 60GB drive has two platters with three heads). I suspect that this is rather common.
I'm sorry I can't log in at the moment but ... The above may be true for the drives that were made in the 1980s, for the original IBM PC. The values now, make no particular sense that is applicable to all drives from every drive maker. The manufacturer is responsible for making the presentation of the physical disk medium to a place where someone writing operating system level code, can reliably address it. This requires some cooperation from the BIOS folks who have traditionally been responsible for reporting the correct disk size, to the OS. As of the Vista version of the Windows OS, Windows will began to assume some of the responsibility for obtaining information from the BIOS. (There was a time when no BIOS had a setting that pertains to a PnP OS). Linux has ignored BIOS settings for quite some time. These things aside, it is clear that some contributors do not even know. A track and a cylinder are definitely /not/ the same thing but I just saw text that says they are. In addition, the drawing of the platters for this entry should show the platter stack from an oblique angle so that the drawing is not misinterpreted to say the same thing. To add to this, since a floppy is always a single platter, the number of cylinders is the same as the number of tracks (as the definition I read and changed stated) if the platter can hold data on one side, only. Probably the only thing that persists is that there is one head per writable side of each platter. The point to make clear is that the heads are not part of the disks, or of the disk stack, although they are part of the drive. —Preceding unsigned comment added by 67.40.35.153 ( talk) 04:35, 20 November 2008 (UTC)
This article might want to mention something about how the cylinders, heads and sectors are counted. I was just reading about the classical PC (DOS) partition table and how the first sector is located at cylinder 0, head 0, sector 1 (CHS 001). This is where the master boot record (MBR) is stored. However, the address CHS 000 seems to be illegal. Are all CHS addresses ending in 0 invalid, or just this first one? -- Jwinius 15:49, 19 April 2007 (UTC)
1. Cylinder: 0 - 1023 (for a maximum total of 1024). 2. Head: 0 - 254 (for a maximum total of 255). 3. Sector: 1 - 63 (for a maximum total of 63).
As one proceeds through LBA counts of 0, 1, 2, etc., the following are a few corresponding CHS tuples that may be very helpful in understanding their relationship (for drives that have 63 sectors per head):
LBA 0 = CHS 0,0,1 LBA 62 = CHS 0,0,63 LBA 63 = CHS 0,1,1
Likewise, for drives that have a pseudo-geometry of 255 heads per cylinder (which may be determined by your operating system these days; e.g., many Linux installs are based on only 16 heads/cylinder, whereas the same physical disk might have 255 heads/cylinder under a Windows OS), the following would be true:
LBA 16,002 = CHS 0,254,1 LBA 16,064 = CHS 0,254,63 LBA 16,065 = CHS 1,0,1
And the maximum LBA sector that CHS can provide a valid corresponding tuple for is at: CHS 1023,254,63 which is equivalent to an LBA of 16,450,559 for 16,450,560 sectors, total; which was passed when hard disks began to exceed a size of 8,422,686,720 bytes, (about 8.42 GB; or 7.84 GiB). Daniel B. Sedory 22:31, 10 June 2007 (UTC)
NOTE: All of the above and more has been added to the article since Jwinius asked about it. Daniel B. Sedory 27 November 2008.
Just a quick note here to mention that I'll be slowly merging the small amount of material at Disk sector into various sections here. Any comments would be appreciated. Daniel B. Sedory 19:27, 7 October 2007 (UTC)
When I started editing this article, its use of the term 'Sector' in CHS (Cylinder,Head,Sector) as the geometrical sector (or slice) common to mathematics, etc. was (and still is) rather compelling. So, I kept that usage as best I could even when adding content to the article Disk sector; based upon what I'd read here and in Circular sector. As a reflection on this topic, I'm asking (musing) whether or not block should continue being used here as the smallest 'chunk of data' one can 'read from/write to' an HDD through its interface (controller card), and how best to point out that 'Sectors' in CHS notation doesn't necessarily mean the same thing as Sectors in HDD capacity calculations. I'm still thinking this through but wanted to present some data and ideas concerning this.
One possible reason the use of "block" was replaced by the now more common term "sector," may be that 'block' was viewed as being somewhat artificially inserted into formulas for computing a disk's capacity: We know many of these formulas use the pseudo drive values of: "63 sectors" and "255 heads," but what units are associated with them? If we use a formula often found in simplified web presentations: S sectors/head x H heads/cylinder x C cylinders
, we can't help but notice both the 'head' and 'cylinder' units cancel each other out, giving us S x H x C sectors
; apparently keeping all the units straight. But do these units actually correspond with reality?
Did the change from the real number of physical 'sectors' and drive 'heads' (perhaps when Zone bit recording became standard on all new HDDs?) signal the rise of 'sectors' vs. 'blocks'?
The formulas presented in this article arrive at drive capacity from some physically real units that still apply to floppy diskettes: S SectorSlices/Side x H Sides x C Cylinders = S x H x C (SectorSlices x Cylinders)
(where Side is equivalent to 'head'). The only way to resolve this result into a single unit is by defining another term as equivalent to "SectorSlices x Cylinders"; which this article does by stating:
blocksPerPlatterSide = (cylindersPerPlatter)*(SectorsPerPlatter)
which is directly related to its definition of block as: The intersection of a cylinder and a sector (SectorSlices x Cylinders). So, what's wrong with the first formula I presented here from popular web sites? I'll have to leave that for another time! Daniel B. Sedory 10:34, 17 June 2007 (UTC)
Αcording to the book "Data Management Systems" 3rd edition, by Ramakrishnan and Gehrke, (pages 306-307): "Each track is divided into arcs, called sectors [...]. The size of a disk block can be set when the disk is initialized as a multiple of the sector size." This is a much different definition than the one given here. What are the sources for the definition of sector and block here? —Preceding unsigned comment added by 195.148.60.152 ( talk) 12:56, 27 October 2008 (UTC)
The article says in section “ Cylinders” that 255 * 63 is 16,064. At least this is the way I understood the wording. Actually, 255 * 63 is 16,065. So, where’s the mistake in the article? If there is a special reason to use 16,064 sectors per cylinder, more explanatory text around that should be added. If the number is wrong, it just needs to be changed.
Please merge the Cylinder (disk drive) stub into this article. – 82.113.99.139 ( talk) 14:18, 30 July 2011 (UTC)
Hi, Ocdex trimmed two occurences of "The in essence" something to "In essence" something in the Heads section, is that as it should be? I undid my "fix" of the 1st case when the 2nd case convinced me that this was an intentional modification. – 89.204.153.138 ( talk) 03:49, 15 September 2011 (UTC)
Is the figure depicting a disk sector accurate? If one read this with the information in the article I'm having a hard time adapting this into a physical reality.
Using the figure:
+-----+ | | Track 1 +-----+
+---------------------------+ | | Track 32 +---------------------------+
Are those two both supposed to hold the same amount of bits? E.g. 512*8?
Are they even larger then 512*8 due to the fact of what is described under disk sectors: "In disk drives, each physical sector is made up of three basic parts, the sector header, the data area and the error-correcting code (ECC)."
[1]
Disk sector: "Thus, the disk sector (Figure 1, item C) refers to the intersection of a track and geometrical sector."
-- Warumwarum ( talk) 11:01, 9 October 2013 (UTC)
Hello fellow Wikipedians,
I have just modified 6 external links on Cylinder-head-sector. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
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have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the
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(last update: 5 June 2024).
Cheers.— InternetArchiveBot ( Report bug) 02:23, 16 August 2017 (UTC)
This article should clarify that "allocation unit", "block", and "cluster" are all terms referring to the same concept on different platforms. And if I'm missing some subtle difference between some of these terms, that should probably also be made clear. Currently different paragraphs use one or two terms and it's not always clear whether or to what extent they are interchangeable. It might be worth noting that some historical systems even used other terms. The term in the TRS-80 world was "granule" and one OS on that platform, NEWDOS/80 even introduced another level of abstraction termed the "lump". — Hippietrail ( talk) 02:59, 13 June 2020 (UTC)
It's a little early in the 2000s to be commenting on the "late 2000s" already. Can this be re-worded? I'm really not sure which time period is being referred to:
but many tools for manipulating the master boot record (MBR) partition table still aligned partitions to cylinder boundaries; thus, artifacts of CHS addressing were still seen in partitioning software by the late 2000s
24.196.190.186 (
talk)
13:24, 26 August 2022 (UTC)