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une · 04-08-2007, 07:05 AM

After much research I still cannot visualize some aspects of hard disk operation. Here are my questions;

1) FORMATTING
When a disk is formatted with a particular file system is the entire surface of the disk changed in some way, or is information deposited in a control portion of the disk. Here are two analogies using a football field as the disk's surface to help describe my understanding;

Analogy a)
Lets say we want to format the football field in NTFS. The greenkeeper goes out and mows the grass in concentric circles. Let's now say we want to reformat it as ext3. The greenkeeper goes out and mows the grass in a criss-cross pattern.

Analogy b)
Lets say we want to format the football field in NTFS. The greenkeeper goes to his office and makes a note in his ground use register that only teams who use NTFS equipment can play on it. Let's now say we want to reformat it as ext3. The greenkeeper goes back to his register and alters the entry to say that only teams who use ext3 equipment can play on it. The grass is mowed any way the lawn mower feels like on the day, it makes no difference.

Which analogy is more correct?

2) PARTITIONING
When a disk is partitioned do the file systems of each partition have to be decided upon when partitioning? What exactly defines a partition? Is a partition defined by what we could call a "line"? Or is it defined as a series of addresses held in a control sector of the disk? Let's go back to the football field analogy.

Analogy c)
The greenkeeper wants to split the football field into 3 fields, 2 half size soccer fields (2 x NTFS) and a half size hockey field (1 x ext3). So he draws 2 permanent dividing lines on the grass. At this point the field is divided (partitioned) but their use has not yet been designated (not formatted yet). Can a disk be partitioned without formatting the partitions?

Analogy d)
The greenkeeper wants to split the football field into 3 fields, 2 half size soccer fields (2 x NTFS) and a half size hockey field (1 x ext3). So he mows 2 areas concentrically (for soccer = NTFS) and mows one in criss cross (for hockey = ext3). Then he makes notes in his register regarding which area is for which sport . There are no "lines" on the grass to be seen.

Which analogy is more correct? Is the partition defined by a "line" between the separate sub-fields, or is it defined by the state of the surfaces of each sub-section of field, or is it defined by information held in a central "control sector", or is the partition defined via a combination of these three aspects?

3) FILE SYSTEMS
How the different file systems work has me puzzled. For example on a disk containing 2 operating systems (say Linux and Windows) the operating systems can see the partitions, but cannot recognize a foreign file system. This leads to to think that a partition consists of a figurative "line" marked on the disk. Or are the partitions defined by information stored in a central disk management sector that Windows for example would read and see "from sector aaa000 to sector adr234 is NTFS, sectors adr235 to zzz999 are foreign to me but I know they are in a separate partition." Linux would read the same disk management sector and see "from sector aaa000 to sector adr234 is something I cannot recognize but I know they are in a partition of their own, sectors adr235 to zzz999 are ext3 and I can use these." Thus an operating system cannot read a foreign file system, but partitions are OS independent. Is this correct?

Say I create a few NTFS partitions on my HD using Windows. I examine the same HD with Linux. Linux can see it has been partitioned but cannot read any data because the file system is foreign. Can Linux then reformat one of these partitions to ext3? If so would this change the partitioning definitions?

Good luck. I have yet to find anyone who can explain in plain English how the three concepts of partitions, file systems and formatting all hang together.

04-08-2007, 07:05 AM	#1 (permalink)
une Registered User Join Date: Apr 2007 Posts: 3 OS: Linux/XP	Formatting, partitions & file systems After much research I still cannot visualize some aspects of hard disk operation. Here are my questions; 1) FORMATTING When a disk is formatted with a particular file system is the entire surface of the disk changed in some way, or is information deposited in a control portion of the disk. Here are two analogies using a football field as the disk's surface to help describe my understanding; Analogy a) Lets say we want to format the football field in NTFS. The greenkeeper goes out and mows the grass in concentric circles. Let's now say we want to reformat it as ext3. The greenkeeper goes out and mows the grass in a criss-cross pattern. Analogy b) Lets say we want to format the football field in NTFS. The greenkeeper goes to his office and makes a note in his ground use register that only teams who use NTFS equipment can play on it. Let's now say we want to reformat it as ext3. The greenkeeper goes back to his register and alters the entry to say that only teams who use ext3 equipment can play on it. The grass is mowed any way the lawn mower feels like on the day, it makes no difference. Which analogy is more correct? 2) PARTITIONING When a disk is partitioned do the file systems of each partition have to be decided upon when partitioning? What exactly defines a partition? Is a partition defined by what we could call a "line"? Or is it defined as a series of addresses held in a control sector of the disk? Let's go back to the football field analogy. Analogy c) The greenkeeper wants to split the football field into 3 fields, 2 half size soccer fields (2 x NTFS) and a half size hockey field (1 x ext3). So he draws 2 permanent dividing lines on the grass. At this point the field is divided (partitioned) but their use has not yet been designated (not formatted yet). Can a disk be partitioned without formatting the partitions? Analogy d) The greenkeeper wants to split the football field into 3 fields, 2 half size soccer fields (2 x NTFS) and a half size hockey field (1 x ext3). So he mows 2 areas concentrically (for soccer = NTFS) and mows one in criss cross (for hockey = ext3). Then he makes notes in his register regarding which area is for which sport . There are no "lines" on the grass to be seen. Which analogy is more correct? Is the partition defined by a "line" between the separate sub-fields, or is it defined by the state of the surfaces of each sub-section of field, or is it defined by information held in a central "control sector", or is the partition defined via a combination of these three aspects? 3) FILE SYSTEMS How the different file systems work has me puzzled. For example on a disk containing 2 operating systems (say Linux and Windows) the operating systems can see the partitions, but cannot recognize a foreign file system. This leads to to think that a partition consists of a figurative "line" marked on the disk. Or are the partitions defined by information stored in a central disk management sector that Windows for example would read and see "from sector aaa000 to sector adr234 is NTFS, sectors adr235 to zzz999 are foreign to me but I know they are in a separate partition." Linux would read the same disk management sector and see "from sector aaa000 to sector adr234 is something I cannot recognize but I know they are in a partition of their own, sectors adr235 to zzz999 are ext3 and I can use these." Thus an operating system cannot read a foreign file system, but partitions are OS independent. Is this correct? Say I create a few NTFS partitions on my HD using Windows. I examine the same HD with Linux. Linux can see it has been partitioned but cannot read any data because the file system is foreign. Can Linux then reformat one of these partitions to ext3? If so would this change the partitioning definitions? Good luck. I have yet to find anyone who can explain in plain English how the three concepts of partitions, file systems and formatting all hang together.