259 replies to this topic

[Wonko the Sane]

JFYI:
http://www.osronline...icle.cfm?id=107

In all versions of Windows NT as well as Windows 2000 and Windows XP, drive letters are nothing more than “symbolic links” in the object manager name space.

Multiple mountpoints:
http://msdn.microsof...y/ff567603.aspx


Wonko

[karyonix]

What it does *not* tell you, is that a volume can contain multiple partitions, an extended partition can contain multiple Sub-partitions, and a partition table can contain multiple partition entries.

I don't think so. Volumes are not container of partitions. Partitions are container of volumes.

Basic disks are divided into partitions : primary partitions, extended partition. Extended partition can have logical partitions inside it.
A volume in a basic disk is made of 1 partition.

Dynamic disks contain extents.
A volume can be composed of one or more extents in one or more dynamic disks.
A simple volume is made of one extent in one disk. In this case, extent is an equaivalent of partition.

Normally boot disks are basic disks.

[Wonko the Sane]

....Volumes are not container of partitions. Partitions are container of volumes....
....

Dynamic disks contain extents.
A volume can be composed of one or more extents in one or more dynamic disks.
A simple volume is made of one extent in one disk. In this case, extent is an equaivalent of partition.

Normally boot disks are basic disks.

Wonko

[LeMOGO]

• If
  
• Then

@karyonix

Thanks for this info!
I did not know the terminology "extent". I'd like to do more reading on it. Would you mind posting links for your sources please?

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

I don't think so. Volumes are not container of partitions. Partitions are container of volumes.

First, I was shocked

Dynamic disks contain extents.
A volume can be composed of one or more extents in one or more dynamic disks.
A simple volume is made of one extent in one disk.

Then I was surprised. I learned something new.

But ... then, I kept reading

A simple volume is made of one extent in one disk. In this case, extent is an equivalent of partition.

...and appplied sone logic:

If: A simple volume is made of one extent in one disk.
And: extent is an equivalent of partition
Then: A simple volume is made of one partition in one disk

And

If: A volume can be composed of one or more extents in one or more dynamic disks.
Then: Volumes are containers for extents.

What are extents?
Are they not partitions?
Where do extents come from?
In any case, what you are saying is that extents go in volumes, not the other way around. And if partitions go in extents, which is the container?

[karyonix]

VOLUME_DISK_EXTENTS Structure
http://msdn.microsof...727(VS.85).aspx

Anatomy of LVM
http://tldp.org/HOWT...TO/anatomy.html


An article can span across multiple pages.
Article is not container of pages.
Article is content. Collection of pages are container of article.

[Wonko the Sane]

Let's introduce another neologism

A partition contains a volume.
A sub-partition contains a volume.
An extent is a volume.
In the case of a primary partition, partition=extent=volume.
In the case of a logical volume inside Extended partition, sub-partition=extent=volume.
You can create a "super-volume" adding together more than one volume.
A filesystem is applied to the volume.
In the case of Basic Disks filesystem=volume.
In the case of Dynamic Disks filesystem=super-volume.


Wonko

[sambul61]

Let's introduce another neologism

An extent is a volume.

Extent is defined not as a volume, but rather an isection of hard drive space, which is smaller than an ordinary Partition and is added to a dynamic volume allowing it to grow in increments when needed.

"Each physical volume is divided into chunks of data, known as physical extents".

Not sure though, how this multi-post philosophical excurse is relevant to the thread topic. But I wouldn't argue with Karyonix on that definition, he feels it on his fingertips - they call it "practical experience".

[sambul61]

duplicate - pls remove.

[LeMOGO]

VOLUME_DISK_EXTENTS Structure
http://msdn.microsof...727(VS.85).aspx

NumberOfDiskExtents
The number of disks in the volume (a volume can span multiple disks).

An extent is a contiguous run of sectors on one disk.

so is a partition. What's the difference? None from the grouping of sectors stand point. An extent is a partition. It might not be created in MBR or PBR, but it is still a partition: a contiguous collection of sectors. If you really want to get technical, then we have to say that it is a sub-partition. But a sub-partition is a partition: a collection of contiguous sectors.

That's what goes for Microsoft.
Now on to Linux:

Anatomy of LVM
http://tldp.org/HOWT...TO/anatomy.html

3.2. physical volume (PV)
A physical volume is typically a hard disk, though it may well just be a device that 'looks' like a hard disk (eg. a software raid device).

Here the disk is assigned to the volume. The volume is made out of disk (1).
This also says that from a volume stand point, anything that "looks" like a disk is fair game. It will accept it as a component of the volume.

3.3. logical volume (LV)
The equivalent of a disk partition in a non-LVM system. The LV is visible as a standard block device; as such the LV can contain a file system (eg. /home).

Here, the volume is clearly what gets "formatted", just like a regular old partition. That's all it says, it does not define what a logical volume is, but we will get a better understanding in 3.6. We can however deduce that a logical volume is what the OS will see as "the storage".

3.4. physical extent (PE)
Each physical volume is divided chunks of data, known as physical extents, these extents have the same size as the logical extents for the volume group.

Each hard disk (or raid) is divided (there is a word missing here, I will assume it is "into") chunks of data, known as physical extents. We saw in the first definition that: "An extent is a contiguous run of sectors on one disk." Disks are divided into sectors. Sectors are grouped for use by file systems. In FAT, they are grouped into clusters. In Linux Logical Volume Management, they are grouped into physical extents. Physical extents are clusters of sectors. A physical extent is a sub-division of a physical volume which is anything that will behave as a group of contiguous sectors (disk, partition, ...).

3.5. logical extent (LE)
Each logical volume is split into chunks of data, known as logical extents. The extent size is the same for all logical volumes in the volume group.

We saw previously that term logical volume (LV) has still not been defined up to this point. It is still the case here.
3.5 tells us that each volume is logically split. That logical subdivision is called a logical extent. So, we could say that a logical volume is a container of logical extents. A logical extent is a sub-division of a logical volume.

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.
Physical extents (clusters of sectors) are inside physical volumes (disks, partitions ...).
Logical extents (storage units) are inside Logical volumes ("the storage").

3.6. Tying it all together
A concrete example will help:

Let’s suppose we have a volume group called VG1, this volume group has a physical extent size of 4MB. Into this volume group we introduce 2 hard disk partitions, /dev/hda1 and /dev/hdb1. These partitions will become physical volumes PV1 and PV2 (more meaningful names can be given at the administrators discretion). The PV's are divided up into 4MB chunks, since this is the extent size for the volume group. The disks are different sizes and we get 99 extents in PV1 and 248 extents in PV2. We now can create ourselves a logical volume, this can be any size between 1 and 347 (248 + 99) extents. When the logical volume is created a mapping is defined between logical extents and physical extents, eg. logical extent 1 could map onto physical extent 51 of PV1, data written to the first 4 MB of the logical volume in fact be written to the 51st extent of PV1.

3.1. volume group (VG)
The Volume Group is the highest level abstraction used within the LVM. It gathers together a collection of Logical Volumes and Physical Volumes into one administrative unit.

VG Administrative unit = collection of Logical Volumes and Physical Volumes
VG Administrative unit = collection of Logical Volumes (disk partitions) and Physical Volumes (hard disks)

Tying it all together:
In this example, we're creating a volume group called VG1 (with physical extent size defined as 4MB)

hard disk partition /dev/hda1 = PV1 => placed in VG1 (seen as hard disk)
hard disk partition /dev/hdb1 = PV2 => placed in VG1 (seen as hard disk)
VG1 = PV1+PV2
VG1 extent size = 4MB => (PV1+PV2) are divided up into 4MB chunks (kind of like FAT clusters)
PV1/4MB = 99 extents
PV2/4MB = 248 extents
VG1 = PV1+PV2 = 99+248 = 347 extents
LE (logical extents) = blocks of logical volume
PE (physical extents) = blocks of the disks or partitions
L VOLUME = what's accessible from the OS = subdivided in LE(s) = group of LE(s) = container of LE(s)
LE(s) are in LV(s)
LE(s) are mapped to PE(s) which are groups of sectors.
sectors go into PE. Each PE goes into a LE. LEs go into LV.
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).

An article can span across multiple pages.
Article is not container of pages.
Article is content. Collection of pages are container of article.

An article is a collection of words.
Article is the container for words.
Words go into articles.

Pages hold articles.
Pages are containers for articles.
An article can span multiple pages because pages break articles into chunks. That does not change the fact that the thing called "page" was created to hold and display articles.

I still can't see how volumes don't contain partitions (contiguous blocks of sectors), regardless of what volume you look at. 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". I don't mind being wrong (in which case I will quickly adjust), but you have to show me where I'm wrong.

Good discussion so far.
Thank you all.

[Wonko the Sane]

I'll try again .
In Basic disks:

• Disk contains one or more partition
  
• A partition is defined by a partition table entry that identifies a contiguous number of sectors (extent).
  
• A primary partition is EXACTLY the same thing as a volume.

In non-partitioned media:

• Disk contains one single volume.

In Dynamic Disks:

• *something* defines more that one set of contiguous number of sectors (partitions or extents), even of different disks, as a "dynamic partition" or volume ("super-volume").

The problem comes with Extended partitions:

• An Extended partition, contains one or more "sub-partition" or one or more volumes.
  
• A "sub-partition" (as defined earlier) contains one volume.
  
• The difference is that UNLIKE with primary partitions, first sector of an Extended partition contains a "partition table" as well as first sector of each of the "sub-partitions".
  
• In these cases, the partition or "sub-partition" "contains" the volume.

Anything that has as first sector a bootsector or PBR (partition boot record) or VBR (Volume boot record) BPB (Bios Parameter Block) :
http://homepages.tes...eter-block.html
is a Volume or partition, or "super-volume" or filesystem (once formatted).

I have to remind the history.
First came the UNpartitioned media, that could ONLY have a Volume.
Then came partitioning, that could ONLY have partitions=Volumes (ONLY primary).
Then came Extended partition (as a workaround) that created and external partition to contain other partitions=volumes.
Then came Dynamic disks that created the possibility of having "super-volumes" made by summing together extents or partitions or volumes.

The volume was born BEFORE anything else, the partition was created after and initially coincided perfectly with the volume and "contained" logically the volume. Later, with the advent of extended partition, the partition was larger and actually contained the volume.
Dynamic disks came many years later and gave the possibility to assemble together extents (or partitions or volumes) into a "super-volume".

If you are convinced that a volume contains a partition, remember that you need to change a couple terms used in 99.99% of all the documentation ever available:
in Basic Disks, in the MBR and in the EPBR's there is NO "partition table" made of up to four "partition entries", but rather a "volume table" made of up to 4 "volume entries" .
And of course you will need to rename:

• Parted magic to Volumeed Magic
  
• Partition Magic to Volume Magic
  
• PTEditor to VTEditor
  
• Paragon Partition Manager to Paragone Volume Manager
  
• Diskpart.exe to DiskVol.exe
  
• ... to ....

(in practice only Acronis Disk Director wouldn't change name )

What's in a name? that which we call a rose
By any other name would smell as sweet;

So, we can well start calling roses cucumbers and cucumbers lemons, but I guess that we'll have some problems in understanding each other

As always OT , but not much:
http://thelazyadmin....asic-Disks.aspx


Wonko

[LeMOGO]

In basic disk

• A primary partition is EXACTLY the same thing as a volume.

Why?

In non-partitioned media:

• Disk contains one single volume.

Why?

The problem comes with Extended partitions:

• An Extended partition, contains one or more "sub-partition" or one or more volumes.
  

Why?

I have to remind the history.
First came the UNpartitioned media, that could ONLY have be in a Volume.
Then came partitioning, that could ONLY have one partitions=Volumes (ONLY primary).
Then came Extended partition (as a workaround) that created and external partition to contain other partitions=volumes.
Then came Dynamic disks that created the possibility of having "super-volumes" made by summing together extents or partitions or volumes.

<= true, you can put a volume into a super-volume, that's what volumes are for, just like you can put a folder in a folder.

The volume was born BEFORE anything else

so it's not a partition

the partition was created after

so it's not a volume

and initially coincided perfectly with the volume

Why?

and "contained" logically the volume.

Why? Because MS could only do 1 partition per volume.
In those very same days, I was taking partitions and throwing them into volumes in Novell. When win2k came around, i remember thinking to myself, "it's about time these guys finally caught up". They were years behind.

Later, with the advent of extended partition, the partition was larger and actually contained the volume.
Dynamic disks came many years later and gave the possibility to assemble together extents (or partitions or volumes) into a "super-volume".

If you are convinced that a volume contains a partition, remember that you need to change a couple terms used in 99.99% of all the documentation ever available:
in Basic Disks, in the MBR and in the EPBR's there is NO "partition table" made of up to four "partition entries", but rather a "volume table" made of up to 4 "volume entries"

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.

It boils down to this:
Key question one: how is a volume created?

Key question two: what *is* a volume? We need to define the term irrespective of partitions or drives, because they are not drives, nor are they partitions.
Please complete this sentence in just a few words:
A volume is ...

[Wonko the Sane]

I guess that there is no possible way to try and come to any kind of agreement on this particular topic any further.

As said, if you are happy to think that a volume contains a partition, be happy with it.

If you want to change names to things, no matter if these names were used in a given manner in everything ever published till yesterday, you are also welcome to do so.

As said before, and as I see it, if you introduce neologisms it's OK, it's "new information", if you exchange existing names, you will contribute to chaos and misunderstandings, exactly the OPPOSITE of the original intention.


JFYI :

• A GLENTAGGART may contain an ADLESTROP.
  
• An ADLESTROP may contain a DORRIDGE.
  
• A FLIMBY is NOT a GLENTAGGART.
  
• A FLIMBY cannot convey a sense of DUNGENESS.
  
• You can YORK a GLENTAGGART but NOT a FLIMBY.
  
• BOTH GLENTAGGARTS and FLIMBIES may contain GLASSELS.

Wonko

[sambul61]

In the case of a primary partition, partition=extent=volume.
In the case of a logical volume inside Extended partition, sub-partition=extent=volume.

The term Extent was fully defined above, its included incorrectly here. Also, the "equal" sign is used incorrectly as well with regards to partitions and volumes.

Partition is a logical storage unit, comprised of a single large section of Physical Drive of non-incremental nature, with size and boundaries selected by a user, usually dedicated to carry a particular type of data.

Logical Volume is a logical drive formatted with a single File System, which can be assigned a drive letter and may be backed up by one (in Basic Storage) or several (in Dynamic Storage) physical drive Partitions and Extents used as storage carriers.

Thus Partitions divide physical storage into chunks, and Logical Volumes organize these chunks into a single logical storage space with common data structure (File System), allowing to access the data and reorganize available physical storage efficiently for a given data collection.

Physical Drive is a physical device, which contains data storage medium (often historically called a Disk due to its original design and work principles) that may be divided into one or more storage units (Partitions and Extents) serving as data carriers for Logical Volumes used to organize and access that data.

Physical Volume is a derivative term usually referring to a single physical storage unit - Physical Drive or Partition, while Physical Volume Group - to a group of storage units comprising a RAID Massive.

Virtual Drive is a Logical Volume, in which an image file of a drive substitutes physical drive Partition(s) and Extent(s) by means of Disk Emulator.

[Wonko the Sane]

The term "extent" was fully addressed above, its included incorrectly here. Also, the "equal" sign is used incorrectly as well with regards to partitions and volumes.

Sure , that's exactly the idea of my signature.


Wonko

[sambul61]

As they say, "with all due respect", yours truly, nothing personal.

[Wonko the Sane]

As they say, "with all due respect", yours truly, nothing personal.

Of course nothing personal, though I still wonder how out of two people trying to say the SAME thing (karyonix and yours truly ) one of the two is right and the other is wrong.

In any case should anything in my previous posts have conveyed any different impression, my personal view is 100% identical to the one karyonix expressed in post #102:
http://reboot.pro/13676/page__st__101


Wonko

[sambul61]

In any case should anything in my previous posts have conveyed any different impression, my personal view is 100% identical to the one of karyonix

Oh my dear self-proclaimed Mozart! How these stupid low life shameless pretzel Salieries could possibly bring a shadow over your tantalizing shininess!?

[Wonko the Sane]

Oh my dear self-proclaimed Mozart! How these stupid low life shameless pretzel Salieries could possibly bring a shadow over your tantalizing shininess!?

I really don't know WHAT THE HECK are you talking about.

If you fancy to compare me to any of the people at the Vienna's court at the end of the 18th Century, JFYI, I would be more like Lorenzo Da Ponte:
http://en.wikipedia....orenzo_Da_Ponte



Wonko

[sambul61]

I would be more like Lorenzo Da Ponte:
http://en.wikipedia....orenzo_Da_Ponte

I know...

"Da Ponte travelled to Austria, and applied for the post of Poet to the Theatres. Emperor Joseph II asked how many plays he had written. Da Ponte replied "None, Sire", to which the Emperor replied "Good, good! Then we shall have a virgin muse."... All of Da Ponte's works were adaptations of pre-existing plots, with the exceptions of L'arbore di Diana with Vicente Martín y Soler, and Così fan tutte, which he began with Salieri, but completed with Mozart."

Just kidding, my dear. I'm not "with, identical or behind" anyone... Just a big follower (as you noted) of your enlightening publications.

[LeMOGO]

can't type long. i'm on hwy driving.
But I've got to say this: I was beginning to wonder why we were not getting the regular janitorial svces.

[sambul61]

To be brief: one must not be a full blown as*hole to figure this out. But...I can regularly refresh odor from that one, if you insist. Looking more closely at what we were missing before one's highness came here with "A global theory from an infant".

[Wonko the Sane]

I wonder if any of the peeps at Wikipedia would care to add a reference to this thread to the article :
http://en.wikipedia....Troll_(Internet)



Wonko

[LeMOGO]

@sambul61,
I was actually glad to see you around. I was simply jokingly asking why you had not posted for so long, that's all. The last time you posted you asked me to get ready for your account, and then vanished. I have been waiting since then.
To be clear, I simply asked why you were not answering as usual.
However, you are free to think as yourself. One thing I do not do is engage in foul language contest. Since you have chosen to be rude, consider this my last post concerning you.
I understand now why wonko will deal with thousands of readers everyday for over half a decade, but one, and only one, made it as a disclaimer in his signature:

WARNING:
it is very likely that the above post:

* contains unneeded, superfluous, out of topic or plainly wrong info, posted thoughtlessly and unneededly to the only scope of confusing other people or making their life more difficult
* for posts after December 20th, 2010 - it is followed by a comment by someone that explains the above and suggests what I should post and how

this signature was added in order to easen the efforts of anyone willing to better me or the quality of my contributions, I am too old and stubborn to change my way of being.

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

@wonko,
I have been tied up lately, it's difficult for me to post. I will turn my attention to it again this week.
I intend to reread from further back, and review all the links offered about volume because 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. The reason why I went in details was to show you the thinking process I went through, so you can follow along. You did not mention any of it in your response. If I read the articles wrong, you should be able to point to the line that I misread (reason why I went through it line by line). I really still don't see it. Is there such a thing as a volume or not? If so, what is it? 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.

One thing that might help is for us to look at the volume creation process. How are volumes created?

[Wonko the Sane]

I really still don't see it. Is there such a thing as a volume or not? If so, what is it? 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.

As I see it you are falling into a perception error , you assume that:

• a Partition is something that can be defined in all contexts with the same unique definition
  
• a Volume is something that can be defined in all contexts with the same unique definition

It is simply not like that.

• A Primary partition on a basic disk starts with a bootsector (partition bootsector or Volume bootsector) and ends with last sector of the Volume it contains (See note below ¹) Start and ending LBA addresses of BOTH the Primary partition and of the volume are the same)
  
• An Extended partition on a basic disk starts with a EPBR and is followed by a number of hidden, unused sectors, usually 62, before the actual beginning of the first Volume inside it and ends with last sector of the last Volume it contains (See note below ¹)
  
• A sub-partition inside Extended partition starts with a EPBR and is followed by a number of hidden, unused sectors, usually 62, before the actual beginning of the only Volume inside it and ends with last sector of the only Volume it contains (See note below ¹)

• A volume on a basic disk (on a primary partition) IS a Primary partition and IS INSIDE it at the same time (physically and by their address on disk)
  
• A volume on a basic disk (first in an extended partition) is INSIDE the partition (physically and by their address on disk)
  
• A volume on a basic disk (non-first in an extended partition) is INSIDE BOTH the partition and it's "sub-partition" (physically and by their address on disk)

If you prefer:

• A volume on a basic disk (on a primary partition) starts at the SAME LBA address and ends at the SAME LBA address of the partition
  
• A volume on a basic disk (first in an extended partition) starts at a bigger LBA address then the partition start and ends at the same or at a lower LBA address than the partition end.
  
• A volume on a basic disk (non-first in an extended partition) starts at a bigger LBA address then BOTH the partition start and sub-partition start and ends at the same LBA Address of the partition end or sub-partition end or at a lower LBA address than the partition end.

A volume on dynamic disk is simply DIFFERENT, and needs either to be defined differently in the different context it is or a neologism needs to be used (like the proposed "super-volume" ).

Note ¹:
This is actually NOT true for all filesystems.
In basic disks, in partitions that contain volume(s) formatted with the NTFS filesystem the Volume accessible space is 1 sector less than the size of the partition or sub-partition, i.e. AFTER the end of the Volume there is one sector that is inside the partition or sub-partition but outside the Volume (mirror of the Volume or partition bootsector or PBR).



Wonko

[LeMOGO]

As I see it you are falling into a perception error

This might be true, and I am trying to avoid it, but I need to replace it with something!.

you assume that:

• a Partition is something that can be defined in all contexts with the same unique definition
  
• a Volume is something that can be defined in all contexts with the same unique definition

Finally!
That's exactly what I have been saying. Now we are addressing the potential error. So far, from all the information provided, there was nothing that contradicted that.

It is simply not like that.

I will give it some thought. I need to decide if volumes need to be treated as a branch or not. Based on what you are saying, I might have to have it as sub-ranches that we will have to be defined in context.

I still have a few things unclear.
In the above post, you are addressing basic disks (Microsoft context). What you are proposing is the volume can not be defined except it is in a context. I can live with that. However, a volume on a primary partition being both the partition and inside the partition is confusing. If I'm looking at "volume", what am I looking at/for? How do I make the difference? (no wonder there is so much confusion)
Then, on the same disk, it's yet another thing when looking at extended partitions. Something does not seem right.
From the definitions of the boundaries, considering the partition definitions and hidden sectors, I finally understand why you say it's "inside" the partitions. 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? Maybe I got it wrong, but if you know the answer, the question I have is: why do we need volumes?

I will reconsider and ponder this.
Later for now!