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The boot process: a step by step approach to booting.


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#201 LeMOGO

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Posted 24 February 2011 - 03:47 PM

There is no such thing in DOS (and Win9x/Me), NO "symlinks", just a drive (or partition) and it's drive letter.

Well, that's the point. It's in there.The drive letter comes from the "service". That layer. That's what my problem is. How do we handle that? That's what the volume is, the one that gets the letter. It maps letter, file names, directories to the partition. It has to be there so you can assign the partition to it!

I still don't understand what the heck you are up to. :dubbio:

My idea was that this part of "The map" should provide the means to try and clear how the SAME thing can be called with different names (in the same or in different contexts), i.e. provide a way to be able to still read and understand the existing documentation (a large part of which is of MS origin or based on observation made on MS Operating Systems) without the need to re-write it all anew.
Some sort of glossary, or if you prefer "translation table"...


we're on the same page, irrespective of the volume. Besides, we can always add it later :diablo:
Right now, I can't focus on the map, but I can focus on you! :smiling9:
So, you don't agree that the service is a layer because we're in DOS? Monolithic does not mean nonexistent. All it takes is a few lines of code.
What sayest thou? :D

I'll wait and see. :cheers:


Naaaah! You can't wait and "see", it's *your* map! :cheers:

#202 Wonko the Sane

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Posted 24 February 2011 - 04:07 PM

Well, that's the point. It's in there.The drive letter comes from the "service". That layer. That's what my problem is. How do we handle that? That's what the volume is, the one that gets the letter. It maps letter, file names, directories to the partition. It has to be there so you can assign the partition to it!

WHICH service? :dubbio:
Directories and files are NOT mapped to a partition!
They are mapped INSIDE the filesystem (which is applied to the partition).
Partitions are not "assigned", they are defined in the MBR (or EPBR/EMBR).
They are there even WITHOUT any drive letter assigned.
See the previous exchange with TheK about dsfi and \\.\PhysicalDrive and \\.\LogicalDrive.

So, you don't agree that the service is a layer because we're in DOS? Monolithic does not mean nonexistent. All it takes is a few lines of code.

Which service? :cheers:
Something for you courtesy of the Wayback Machine:
http://web.archive.o...s.com/LetAssig/

What sayest thou? :smiling9:

Nothing.

Naaaah! You can't wait and "see", it's *your* map! :cheers:

Oh, yes I can :D , just wait and see. :diablo:

:cheers:
Wonko

#203 karyonix

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Posted 24 February 2011 - 04:15 PM

One device can have multiple drivers operate its different functions.
Multiple layers of drivers are used to run each drive.
Devices of different kinds that have some same functionality can share some drivers.

Drive letters are not volumes. They are is just names or links.
Each letter (A-Z) exists before a partition (or other kind of volume) is assigned to it.
When there is no partition (or other kind of volume) assign to a letter, the letter does not refer to any drive.
Drive letters can be assigned to non-volume storages (such as network locations) as well.

#204 sambul61

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Posted 24 February 2011 - 04:35 PM

Drive letters are not volumes.

No-one said so far that a drive letter is by itself equivalent of a Volume. Can you give your own definition or interpretation, what do you think a Logical Volume is? :dubbio:

#205 karyonix

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Posted 24 February 2011 - 05:12 PM

@sambul61
1. I think I was confused by the 2 its in "It has to be there so you can assign the partition to it". Don't worry about it.
2.
A volume is a storage space that can be or has been formatted with a filesystem.
A logical volume is a logical partition.
Another meaning of logical volume is used in Linux LVM. It is a logical block device made of logical extents.

#206 LeMOGO

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Posted 24 February 2011 - 05:25 PM

@wonko
now both of us have to "wait and see"?
:dubbio:
we may end up waiting long!
----------------------------------------------------------------------------

@karyonix
OK, then maybe I'm wrong.
What's in the file system that enables drive letters? Is it not a module that serves as a directory irrespective of what's underneath (network or drive)?
I understand that they call partitions "volumes". But what about the volume itself (or file system "directory" if you will)?
Am I missing something?

@wonko
It's the "INSIDE the file system" thing I keep referring to.

#207 sambul61

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Posted 24 February 2011 - 06:01 PM

A volume is a storage space that can be or has been formatted with a filesystem.
A logical volume is a logical partition.
Another meaning of logical volume is used in Linux LVM. It is a logical block device made of logical extents.

Thanks! Would you agree that Partition term refers to a physical storage, while Volume - to logical storage?

MS IMHO doesn't use term "logical partition", if you mean its different from "physical partition" (being a logical section of a physical storage drive). If you use terms "physical" and "logical" partitions interchangeably, then Logical Volume is IMHO not equivalent to Partition, since MS clearly distinguishes btw these 2 terms in all their docs, whether about Basic or Dynamic disks.

Speaking on a sister topic - about Fast Boot systems, wanted to through in the mix 20Mb EFI System partition that should be mentioned when listing partition types on the Map. I just faced this creature, trying to install ASUS FastBoot utility to my MoBo BIOS, inspired by this endless discussion - it apparently prompts useful actions. :dubbio:

#208 Wonko the Sane

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Posted 24 February 2011 - 06:41 PM

Can we introduce the concept of marriage? :w00t:

Letters A÷Z (and also a÷z) do exist by themselves (LONG before you partition a disk).
Partitions can exist by themselves.
A drive letter may be "married" to a partition (or drive or "simple" volume").
When *something* mounts a partition (or drive or volume) it couples it with a drive letter (or with a mount point, but this is another story).
When the partition (or drive or volume) is unmounted, the letter and the partition get a divorce. :cheers:

A nice example of "confusion":
http://msdn.microsof...785(VS.85).aspx

Posted Image

Three primary partitions and one extended partition on a basic disk using MBR


Each partition, whether primary or extended, can be formatted to be a Windows volume, with a one-to-one correlation of volume-to-partition. In other words, a single partition cannot contain more than a single volume. In this example, there would be a total of seven volumes available to Windows for file storage. An unformatted partition is not available for file storage in Windows.

The math doesn't work that good. :dubbio:
  • 3 (three) primary partitions + 1 (one) Extended partition= 4 (four) partitions
  • 7 (seven) volumes.
  • Since there is a one-to-one correlation volume-to-partition, then 4=7 :w00t:

If you rephrase it, it suddenly almost :cheers: works (and it becomes actually "more" coherent with the picture) :thumbup: :

Each primary partition or Logical drive inside extended partition, whether primary or extended, can be formatted to be a Windows volume, with a one-to-one correlation of volume-to-primary-partition or volume-to-logical-drive. In other words, a single primary partition or logical drive cannot contain more than a single volume. In this example, there would be a total of seven volumes available to Windows for file storage. An unformatted partition is not available for file storage in Windows.

  • 3 (three) primary partitions + 3 (three) logical drives inside Extended partition= 6 (six) *somethings*
  • 7 (seven) volumes.
  • Since there is a one-to-one correlation volume-to-*somethings*, then 6=7 :w00t:
A much better approximation. :diablo:

Please note how the text before the posted image is:

The following figure illustrates an example layout of three primary partitions and one extended partition on a basic disk using MBR. The extended partition contains four extended logical drives within it. The extended partition may or may not be located at the end of the disk, but it is always a single contiguous space for logical drives 1-n.

:rolleyes:

If we ignore the illustrative example picture (or "figure" or "picture" or "diagram" or "illustration") :D and use the descriptive text above we have a 100% accuracy:
  • 3 (three) primary partitions + 4 (four) extended logical drives inside Extended partition= 7 (seven) *somethings*
  • 7 (seven) volumes.
  • Since there is a one-to-one correlation volume-to-*somethings*, then 7=7 :smiling9:

Following, there is another nice example of how things may appear diofferent (beauty is in the eye of the beholder).

The dynamic disk MBR layout looks very similar to the basic disk MBR layout, except that only one primary partition is allowed (referred to as the LDM partition), no extended partitioning is allowed, and there is a hidden partition at the end of the disk for the LDM database. For more information on the LDM, see the Dynamic Disks section.

Which in one of my carpenter's comparisons sounds like:

A hammer looks a lot like a chisel, except that the chisel has a blade, that you cannot use it to drive nails into wood and that it has a cutting edge.


:cheers:

:cheers:
Wonko

#209 karyonix

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Posted 24 February 2011 - 06:48 PM

Nothing in file system enables drive letters.

Storage class drivers floppy.sys, cdrom.sys etc. except disk.sys notify the system of arrival of a volume.
For disk device, its the job of partmgr.sys filter driver and volume managers.
I don't know the detail of how partmgr.sys communicate with volume managers.
Volume manager for basic disk in Windows XP is ftdisk.sys.
Volume manager for dynamic disk in Windows XP is dmio.sys.
Volume manager for basic and dynamic disk in Windows 7 is volmgr.sys.
Upon detection of partition or logical drive in basic disk or dynamic volume in dynamic disk, volume manager create "Generic Volume" device.
Volume manager then notify the system of arrival of a volume.

Upon arrival of a volume, mount manager creates symbolic links (volume name and drive letter) to the volume.
File system is mounted when someone send "create file" request to a volume.
Read this for more information http://msdn.microsof...9(v=VS.85).aspx .

Mount manager's name is misleading. Its job is just creating symbolic links. It has nothing to do with mounting file system.
You can say creating symbolic link is mounting. But it is a different action from file system mounting.

#210 sambul61

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Posted 24 February 2011 - 07:04 PM

Parity btw partitions and volumes will be restored, when counting "logical partitions" inside Extended partition, upon which Logical volumes are mounted. While there is no real need for parity, if one looks at a Logical Volume as means to access data - meaning it must be assigned a drive letter, formatted and mounted to be called Volume. Otherwise merely its unfinished pre-cursor exists, thus leaving data unaccessible on a physical partition.

Further, MS removed support of a multi-partition Volumes in Basic Disks only after introduction of Dynamic Disks. Hence, there is no need to artificially separate these definitions just because of MS marketing stance (irrelevant pearl :dubbio:).

#211 Wonko the Sane

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Posted 24 February 2011 - 07:38 PM

As often happens OT :D (and confusing :dubbio:).

Coincidence:
Seven plus or minus two:
http://en.wikipedia....us_or_minus_two

Wonko loves coincidences. :smiling9:

  • A word can be a chunk.
  • A word contains letters.
  • A letter can be a chunk.
  • A word can have bits.
  • Binary digits have 1 bit each.
  • Decimal digits have 3.32 bits each.
  • Words have about 10 bits each.
  • There is nothing "magical" about the number 7.

:diablo:
Wonko

#212 LeMOGO

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Posted 24 February 2011 - 11:56 PM

Can we introduce the concept of marriage?


Finally!
YAY!
:happy_dance:

Marriage! That's what I'm talking about, in different words. That "marriage" is called a "volume". You end up with volume (file system) married to volume (partition). Hmm hmm! Wait! Is that allowed? Looks like incest to me!

From the link you provided, on Basic and Dynamic Disks:

...the term volume is used to refer to the concept of a disk partition formatted with a valid file system


Also "Basic Disks" section, paragraph 1:

Basic disks are the storage types most often used with Windows. The term basic disk refers to a disk that contains partitions, such as primary partitions and logical drives, and these in turn are usually formatted with a file system to become a volume for file storage.


i.e. (primary partitions / logical drives) + formatted = a volume for file storage :thumbsup:

Marriage!

Posted Image
(that's $ in his hand) :smiling9:

#213 LeMOGO

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Posted 25 February 2011 - 01:35 AM

Nothing in file system enables drive letters.


OK.
What's in the file system that enables drive letters?
Drive letters need to be "enabled", or should I say something in the file system enables letters (not as in create but as in facilitates the use of, enables the use of, makes it possible to). Something in the file system "hooks" those labels (drive letters - label as in something you "stick on"). How do you get the letter to "hook" to the partition in DOS? There's "something" in the file system! Not so?

What's in the file system that enables drive letters? Is it not a module that serves as a directory irrespective of what's underneath (network or drive)?
... what about the volume itself (or file system "directory" if you will)?


------------------------------------------------------------------------------------------

Upon detection of partition or logical drive in basic disk or dynamic volume in dynamic disk, volume manager create "Generic Volume" device.



So, there is a "volume" that's different from partitions (volumes)?

A volume is a storage space that can be or has been formatted with a filesystem.
A logical volume is a logical partition.


It looks like we're on the same page now. Or are we? By "A volume is a storage space", do you mean a logical storage space, or are you talking physical storage space (MS's confusion)?

#214 LeMOGO

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Posted 25 February 2011 - 01:53 AM

this goes in wonko's signature:

Posted Image

and of course, an emoticon: <_<

#215 karyonix

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Posted 25 February 2011 - 05:43 AM

"Generic Volume" is a generic name. It is assigned to volumes of many kinds. Partition is one of them.
When a partition on disk is detected, "Generic Volume" device is created to represent that partition. There is no separate "Partition" device.

Yes, the "device" in OS, the data structure in memory that represent a physical thing, is not the same thing as physical thing.
If you want to say it like that, a USB mass storage device in OS is not USB flash drive, a PCI bus device in OS is not PCI bus in motherboard.

There are many kinds of person : man, woman, boy, girl.
A man is a person. A man is not a separate begin from a person.
The meaning of "man" and "person" are different.
There are also non-man persons. It does not make a man non-person.

#216 sambul61

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Posted 25 February 2011 - 06:44 AM

There is no common resolution to this question, if one tries to build it solely on MS docs. Why? Because not unlike Linux, Windows also has (is) a large set of small tools, many of which were developed by partners (later plaintiffs), whose tools and companies were consumed by MS. Every such time MS had to bend existing terms framework to fit new tools features (like adapted Logical Volume Manager of Veritas Software (diskmgmt.msc - just run it from Win7 Search)) and new marketing moves. MS was never a big fan of standards, instead they usually offered products that become de-facto standards for developers. IE6 is prominent example of their deformed vision on how things should revolve around MS - it negated every possible web standard, while introducing absolute control over web development for 10 years until Opera guys demanded standard compliance through EU Courts (irrelevant pearl of wisdom <_<).

You won't find clean definitions, because MS was never inclined to confine itself into coherent definitions to begin with, acting on principle "pay as you go". They also made anything adapted (like Dynamic Disks from Veritas) proprietary. One way to do it - mix up terms to compile "new" patent claims. So it makes little sense to build generic system of boot terminology solely from MS prospective, especially on this forum.

How about finding commonalities in diversity? :)

Introduction to Logical Volume Management - Distrowatch
Logical volume management - Wiki

#217 LeMOGO

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Posted 25 February 2011 - 02:32 PM

There are many kinds of person : man, woman, boy, girl.
A man is a person. A man is not a separate begin from a person.
The meaning of "man" and "person" are different.
There are also non-man persons. It does not make a man non-person.


Hmmm! I'm afraid I'm not smart enough for this puzzle :dubbio:

But this much I understand:

"Generic Volume" is a generic name. It is assigned to volumes of many kinds. Partition is one of them.
When a partition on disk is detected, "Generic Volume" device is created to represent that partition.

Yes, the "device" in OS, the data structure in memory that represent a physical thing, is not the same thing as physical thing.


bingo! What we've been saying all this time. You see that word volume in there, it's not the same as volume as in partition, and it's not only for partitions. A volume *can be* something else than a partition in this context.
The whole issue started because when you call partitions volumes, it becomes a problem to refer to the "generic volume" when you need to. Notice that it's called a "generic" volume. There is no other name for it. It's a "volume". When you "generically" use the term "volume", that's what it refers to, not the partition called "volume" by Microsoft, *especially* on non-Microsoft OSes.

That's what I've been saying:
post #95:

Sectors are grouped into partitions.
Partitions are grouped into volumes.
A volume can be made from a single or multiple partitions. When the volume contains only one partition, referring to the volume is the same as referring to the partition, but if we want to talk about the partition within the volume, we need to use the term "partition".
A partition is *not* a volume.

A volume is a container for partitions. A partition is a container for sectors. A sector is a container for bytes. A byte is a container for bits. A bit is a state manipulated as datum.
Each is specific.


post 97

Partitions are grouped as a block and assigned file systems, then the block is mounted as a volume accessible through a single mount point called a "Drive Letter", or Drive.


post 100

not making the distinction between volume (which is a logical thing) and partition (which is a physical thing), and, blurring the lines, cause people to not understand that there are "other kinds of volumes". A volume is not a partition. And yes, some are "Dynamic".
...
Yep! Volumes get "mounted". A mount point is not a drive letter. But, ... if you think in terms of volume=drive letter, you will get lost when there is no drive letter. A drive letter was Microsoft's way of labeling mount points, it is merely a label. A label is a label, a mount point is a mount point, a volume is a volume, a partition is a partition, a boot record is a boot record.


post 109

Logical Volumes are made from either whole disk and/or partitions, but you can only access portions called logical extents. So, looking at extents, you will find them in a volume, and, looking at disks or partitions, you will also find them in a volume. The volume is the “thing” that "holds" both. This is just like extended partitions and sub-partitions. Extended partition is the container for sub-partitions. Sub-partitions are inside extended partitions. Extents are inside volumes.
...
The volume is the container. It is a logical structure like a folder in a file system. Files go into folders, does not mean they sit on the same sector. It's a logical organization, not a physical one.

A volume is a logical structure used to contain whatever grouping of sector your OS allows (whole disk, partition, combination of disk & partition).
...

The sectors can come from disk or partition, but the place where they are logically grouped into a file system accessible storage is "the volume".


post 111

Volume are not partitions. A partition table is not a volume table. Volume do not live in partitions. The volumes have been equated to partitions for years because Microsoft could not create intelligent volumes, AND, the volume creation process was automated until win2k. After win2k, they were able to handle intelligent volumes, so the steps were separated and given to the user (even that they will automate to make it easy for you). The fact that they make all choices for people does not means that there are no choices to make. The fact that they line up a volume boundary to that of a partition boundary does not make a volume a partition. You can essentially see the partition as a volume in this case because they have the same boundaries, but this creates confusion. The step was hidden from users, but it existed.


post 123

...I still don't see why, if a volume is something you create independently of partitions for the purpose of accessing (bundles of) partitions, it is the same as a partition.
...
I understand the part where we can call a partition a volume when they both represent the exact same block of sectors, but as soon as you add a few more partitions and/or drives to it, a volume can no longer be viewed as a partition, and I'm sure that it's because it was not in the first place.


post 126

I now understand you. And I agree with the boundaries. I see that you mean physically inside (at least in those simple cases).
The logic of a partition being "assigned" to the volume still works here however. Even if we look at DOS on basic disk, we create a partition with fdisk, then the volume and its label (with format?). We can not access the formatted partition unless we have a volume to handle it in the OS. Isn't the volume the "stuff" that enables you to manipulate the partition?


post 144

The discussion about volumes started when I argued against the use of the term "MBR partition", and summarized my argument at the end of the post as a logical conclusion.
In the same post, I proposed that in order to avoid the confusion that is already out, we distinguish between partitions and volumes because calling partitions volumes when they can be called partitions might create some confusion when we want to talk specifically about volumes as a logical entity, or partitions as group of sectors (not the logical structure volume).

...
A partition can be called a partition, but a volume can be called by no other name. Why not reserve the term for volumes and call a partition a partition?
In order to avoid the confusion in future writings, we need to agree on terms, especially since some of us write documentation for our applications, and others, write tutorials. This one is about the boot process. We are dealing with these items and we will need to define them properly. I have proposed several definitions so they can be torn up.

...
We need to come up with something coherent about volumes.
...
how do we *make sure there is no confusion* about what we are referring to when people might have in their mind that a volume is a partition?

...
The volume as the logical thing is the logical thing.


post 149

On basic disks, you use a volume to access a volume.

...
A problem arises when we ignore the logical layer because the good old MS guys, with their "good intentions" at one point in time, decided to call partitions volumes. People that are coming from other OSes *will* be confused because it makes no sense, and people new to the subject on Microsoft end need to beware because they will be confused when looking at other OSes. Our UFDs do boot to both linux and windows! G4D is getting very popular and is used to boot both!
A distinction and clarification is needed.
We simply need to avoid the error by adding qualifiers going forward.
We just need to define them, that does not mean there has to be a one size fits all "volume". In our context, it is not possible, but we do need to mark territories. I wanted to hear points of view on the matter. I am still awaiting proposals.
I get that there are "volumes=partitions", but how about the volume that is used to access it, the one that gets the label called "drive letter c:"?
What's the best way to proceed?



#218 LeMOGO

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Posted 26 February 2011 - 01:56 PM

Oh, yes I can ;) , just wait and see. :cheers:

:cheers:
Wonko


Wax on, wax off.
My dear favoritest mentor of all times. Is wait-and-seeing the lesson of the day? :smart:

Some people might take it to the next level and make dance moves out of it to come up with the Mr. Wonko dance! :unsure:
Your googl fu might be picked up by bears and chimps. You NEVER know! :loleverybody:

How is your agree fu? :cheers:
Is it this bad?
http://www.youtube.com/watch?v=S66Dyg7qmmg

#219 Wonko the Sane

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Posted 26 February 2011 - 02:13 PM

Since it's repost day:
post #182:

I am waiting to see your full and fully detailed map, to understand what else may be different.


The above meant (and still means) that I perfectly know what you ALREADY posted and that it seems to me mostly void of any usefulness for the intended goal UNLESS and UNTIL you merge all those bits and pieces in a coherent, omnicomprehensive description.

Posted Image

:loleverybody:
Wonko

#220 LeMOGO

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Posted 26 February 2011 - 02:49 PM

:cheers:

Did you click on ALL the links?
I can't believe you're NOT impressed!

--------------------------------------------------------

I still have to finish what's holding me up. I think today is the last day. I've been posting during drink breaks, but that should change next week, and you'll have the items on the map.
Jeee! Can't a man take a break around here? :loleverybody:
(not really a break actually, necessity)

#221 Wonko the Sane

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Posted 26 February 2011 - 03:13 PM

I can't believe you're NOT impressed!

Can't you read? ;)

The hippo wasn't. :cheers:

However :loleverybody: :

Posted Image

:cheers:

:unsure:
Wonko

#222 LeMOGO

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Posted 26 February 2011 - 04:01 PM

:loleverybody: ;) :cheers:

#223 LeMOGO

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Posted 26 February 2011 - 06:06 PM

Can't you read? :w00t:


That's OK.
We have folks from Gaul around here. They have "druides" that make them drink magic potions and their agree fu is stronger:

Posted Image
Posted Image
Posted Image


Aint' I right karyonix?
(sorry, but you can't get away without being picked on a bit :whistling: - your user name made me think of these guys - can I have some magic potion too? I wanna be smart like you! :D )

---------------------------------------------------------------------------------------------

One device can have multiple drivers operate its different functions.
Multiple layers of drivers are used to run each drive.


... so, how do we call the layer that contains the root directory, the one in which the directories and file names are created?

Drive letters are not volumes. They are is just names or links.
Each letter (A-Z) exists before a partition (or other kind of volume) is assigned to it.
When there is no partition (or other kind of volume) assign to a letter, the letter does not refer to any drive.
Drive letters can be assigned to non-volume storages (such as network locations) as well.


don't those "non-volume" storage become "volumes" that we can use?

...
A volume is a storage space that can be or has been formatted with a filesystem.
...


are you talking about the same thing here or are you referring to something else?

Mount manager's name is misleading. Its job is just creating symbolic links. It has nothing to do with mounting file system.
You can say creating symbolic link is mounting. But it is a different action from file system mounting.


Hmmm! :dubbio:
Not sure what this means.
Could you develop that please?
My understand fu is weak here. I'm missing something in between the symlink and the FS. How does the whole thing work (in simple language of course). In "What Happens to File Systems During System Boot"
"File System Recognizer" section, it says:

After system boot, the storage device drivers for all volumes attached to the system are loaded and started. However, not all built-in file systems are loaded, and not all file system volumes are mounted. The File System Recognizer (FsRec) performs these tasks as needed to process IRP_MJ_CREATE requests.
...
The actual boot file system - that is, the file system that mounted the boot volume - is loaded at the start of the boot process.


and I can't quite find my bearings. I need a grand master karyonix to untangle that

"Generic Volume" is a generic name. It is assigned to volumes of many kinds. Partition is one of them.
...
Yes, the "device" in OS, the data structure in memory that represent a physical thing, is not the same thing as physical thing.
If you want to say it like that, a USB mass storage device in OS is not USB flash drive, a PCI bus device in OS is not PCI bus in motherboard.


What's the name of "the data structure in memory"? (no riddles please - my riddle fu is weak)

#224 karyonix

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Posted 27 February 2011 - 03:51 AM

... so, how do we call the layer that contains the root directory, the one in which the directories and file names are created?

File system, I think.

don't those "non-volume" storage become "volumes" that we can use?

No. Shared folders on network don't become volume when we use them.

are you talking about the same thing here or are you referring to something else?

Shared folders on network and volume are not the same thing.

I'm missing something in between the symlink and the FS. How does the whole thing work (in simple language of course).

Objects or symlink that have names in \DosDevices\ directory in Windows object name space are accessible from Win32 applications.
Devices normally have names in \Device\ directory in Windows object name space which are not accessible from applications.
Mount Manager create symlinks in \DosDevices\ directory in Windows object name space, so that Win32 applications can access volumes.
There are also other symlinks created by PnP Manager but users don't usually use them.

When there is a request to open a file that has (volume's device name, or symlink name) at the beginning of the path, file system is mounted. Then, the remaining part of the path is sent to file system driver.

What's the name of "the data structure in memory"? (no riddles please - my riddle fu is weak)

The name of data structure in memory (in Windows) is "device stack" and "device object".
A device stack is composed of one or more device objects :
1 physical device object (created by bus driver or enumerator),
0 or more lower-filter device objects (created by drivers whose names are in LowerFilter value in device's registry key and drivers whose names are in LowerFilter value in device class's registry key),
0 or 1 functional device object (created by driver whose names is Service value in device's registry key),
0 or more upper-filter device objects (created by drivers whose names are in LowerFilter value in device's registry key and drivers whose names are in UpperFilter value in device class's registry key)
A simple device has 1 device stack.

#225 Wonko the Sane

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Posted 27 February 2011 - 08:32 AM

... so, how do we call the layer that contains the root directory, the one in which the directories and file names are created?


File system, I think.

:cheers:

We can say with a righteous degree of approximation that:
....
6. a filesystem contains directories, files and sub-directories
....
8. since a "partition" or "logical volume" or "volume", "extent", "drive" is pretty much useless without a filesystem applied to it, often the term "filesystem" is used - somewhat IMproperly - as a synonym to "partition" (primary only) or "logical volume" or "volume", "extent", "drive".


;)
Wonko




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