| Author |
Message |
Bill Schaible
Guest
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 Posted:
Wed Aug 17, 2005 8:16 am Post subject:
Is there a rigorous definition for 'primary partition' ? |
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For years I've been using boot manager programs with multiple primary
partitions on multiple drives. Or I skip the boot manager and use a disk
editor to change the partition table in some cases. From that perspective I
can't figure out what would be a proper definition for a 'primary'
partition. I just spent hours Googling the subject on the internet and
didn't find a real definition anywhere.
Some facts about a primary partition (PP):
(1) A PP is defined by one of the records in the partition table, as
opposed to a logical volume, which doesn't have a record in the
first physical sector (CHS001) of the drive. However, that's not a
distinguishing feature because an extended partition has a record in CHS001
also.
(2) An extended partition begins with a partition table (in the EMBR), a PP
does not. A true fact, but not a definition.
(3) A PP doesn't necessarily need to contain system files. You can have
the system files on a diskette, and only non-system files on the hard drive,
and still have a workable system - i.e. a PP isn't necessarily bootable.
(4) Maybe you could say it's a partition that's capable of being booted
from if it has the correct system files and data structures. But that seems
like an OS dependent definition. Is there a more rigorous definition
somewhere?
Bill S. |
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Joep
Guest
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| Posted:
Wed Aug 17, 2005 8:16 am Post subject:
Re: Is there a rigorous definition for 'primary partition' ? |
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"Bill Schaible" <mr.correct@comcast.net> wrote in message
news:NdWdncxjguHfQ5_eRVn-ow@comcast.com...
| Quote: | For years I've been using boot manager programs with multiple primary
partitions on multiple drives. Or I skip the boot manager and use a disk
editor to change the partition table in some cases. From that perspective
I
can't figure out what would be a proper definition for a 'primary'
partition. I just spent hours Googling the subject on the internet and
didn't find a real definition anywhere.
Some facts about a primary partition (PP):
(1) A PP is defined by one of the records in the partition table, as
opposed to a logical volume, which doesn't have a record in the
first physical sector (CHS001) of the drive. However, that's not a
distinguishing feature because an extended partition has a record in
CHS001
also.
|
This is why I consider the extended itself a primary partition as well. If
you want you can say that a primary partition is a partition defined in the
partition table in the MBR while it is not an extended partition.
| Quote: |
(2) An extended partition begins with a partition table (in the EMBR), a
PP
does not. A true fact, but not a definition.
(3) A PP doesn't necessarily need to contain system files. You can have
the system files on a diskette, and only non-system files on the hard
drive,
and still have a workable system - i.e. a PP isn't necessarily bootable.
(4) Maybe you could say it's a partition that's capable of being booted
from if it has the correct system files and data structures. But that
seems
like an OS dependent definition.
|
Indeed.
Joep |
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Maxim S. Shatskih
Guest
|
| Posted:
Thu Aug 18, 2005 2:54 pm Post subject:
Re: Is there a rigorous definition for 'primary partition' ? |
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|
The MBR disk structure contains several sectors which are partition tables.
Each of these sectors has 4 entries, and each entry can be:
- empty
- describe the partition
- describe the link to the next PT sector (yes, PT is linked list). This
next PT sector is usually called "extended partition table". There can be only
one such forward link in a PT sector.
The first PT sector is MBR itself - sector 0 of the physical disk.
MS-DOS (including Win98/Me based on MS-DOS) requires that the first PT
sector has only 1 valid partition entry (and possibly the link to the next PT
sector too). The disk layout where the first PT sector describes several
partitions is incompatible with MS-DOS.
--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com
"Bill Schaible" <mr.correct@comcast.net> wrote in message
news:NdWdncxjguHfQ5_eRVn-ow@comcast.com...
| Quote: | For years I've been using boot manager programs with multiple primary
partitions on multiple drives. Or I skip the boot manager and use a disk
editor to change the partition table in some cases. From that perspective I
can't figure out what would be a proper definition for a 'primary'
partition. I just spent hours Googling the subject on the internet and
didn't find a real definition anywhere.
Some facts about a primary partition (PP):
(1) A PP is defined by one of the records in the partition table, as
opposed to a logical volume, which doesn't have a record in the
first physical sector (CHS001) of the drive. However, that's not a
distinguishing feature because an extended partition has a record in CHS001
also.
(2) An extended partition begins with a partition table (in the EMBR), a PP
does not. A true fact, but not a definition.
(3) A PP doesn't necessarily need to contain system files. You can have
the system files on a diskette, and only non-system files on the hard drive,
and still have a workable system - i.e. a PP isn't necessarily bootable.
(4) Maybe you could say it's a partition that's capable of being booted
from if it has the correct system files and data structures. But that seems
like an OS dependent definition. Is there a more rigorous definition
somewhere?
Bill S.
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Bill Schaible
Guest
|
| Posted:
Sat Aug 20, 2005 7:56 am Post subject:
Re: Is there a rigorous definition for 'primary partition' ? |
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|
Thank you for the info. I have another question if you have a minute. You
say:
| Quote: | The disk layout where the first PT sector describes several
partitions is incompatible with MS-DOS.
|
If I have two primary DOS partitions in the first PT sector (the MBR) and I
boot from a DOS floppy disk, how does DOS decide which of the PT entries
will get a drive letter?
TIA Bill S.
"Maxim S. Shatskih" <maxim@storagecraft.com> wrote in message
news:de1lqp$26on$1@gavrilo.mtu.ru...
| Quote: | The MBR disk structure contains several sectors which are partition
tables.
Each of these sectors has 4 entries, and each entry can be:
- empty
- describe the partition
- describe the link to the next PT sector (yes, PT is linked list).
This
next PT sector is usually called "extended partition table". There can be
only
one such forward link in a PT sector.
The first PT sector is MBR itself - sector 0 of the physical disk.
MS-DOS (including Win98/Me based on MS-DOS) requires that the first PT
sector has only 1 valid partition entry (and possibly the link to the next
PT
sector too). The disk layout where the first PT sector describes several
partitions is incompatible with MS-DOS.
--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com
"Bill Schaible" <mr.correct@comcast.net> wrote in message
news:NdWdncxjguHfQ5_eRVn-ow@comcast.com...
For years I've been using boot manager programs with multiple primary
partitions on multiple drives. Or I skip the boot manager and use a
disk
editor to change the partition table in some cases. From that
perspective I
can't figure out what would be a proper definition for a 'primary'
partition. I just spent hours Googling the subject on the internet and
didn't find a real definition anywhere.
Some facts about a primary partition (PP):
(1) A PP is defined by one of the records in the partition table, as
opposed to a logical volume, which doesn't have a record in the
first physical sector (CHS001) of the drive. However, that's not a
distinguishing feature because an extended partition has a record in
CHS001
also.
(2) An extended partition begins with a partition table (in the EMBR), a
PP
does not. A true fact, but not a definition.
(3) A PP doesn't necessarily need to contain system files. You can
have
the system files on a diskette, and only non-system files on the hard
drive,
and still have a workable system - i.e. a PP isn't necessarily bootable.
(4) Maybe you could say it's a partition that's capable of being booted
from if it has the correct system files and data structures. But that
seems
like an OS dependent definition. Is there a more rigorous definition
somewhere?
Bill S.
|
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Bill Schaible
Guest
|
| Posted:
Sat Aug 20, 2005 7:58 am Post subject:
Re: Is there a rigorous definition for 'primary partition' ? |
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|
Thank you for the info.
Bill S.
"Joep" <available@request.nl> wrote in message
news:133eb$4302e54c$3eddca68$13315@nf1.news-service.com...
| Quote: | "Bill Schaible" <mr.correct@comcast.net> wrote in message
news:NdWdncxjguHfQ5_eRVn-ow@comcast.com...
For years I've been using boot manager programs with multiple primary
partitions on multiple drives. Or I skip the boot manager and use a
disk
editor to change the partition table in some cases. From that
perspective
I
can't figure out what would be a proper definition for a 'primary'
partition. I just spent hours Googling the subject on the internet and
didn't find a real definition anywhere.
Some facts about a primary partition (PP):
(1) A PP is defined by one of the records in the partition table, as
opposed to a logical volume, which doesn't have a record in the
first physical sector (CHS001) of the drive. However, that's not a
distinguishing feature because an extended partition has a record in
CHS001
also.
This is why I consider the extended itself a primary partition as well. If
you want you can say that a primary partition is a partition defined in
the
partition table in the MBR while it is not an extended partition.
(2) An extended partition begins with a partition table (in the EMBR), a
PP
does not. A true fact, but not a definition.
(3) A PP doesn't necessarily need to contain system files. You can
have
the system files on a diskette, and only non-system files on the hard
drive,
and still have a workable system - i.e. a PP isn't necessarily bootable.
(4) Maybe you could say it's a partition that's capable of being booted
from if it has the correct system files and data structures. But that
seems
like an OS dependent definition.
Indeed.
Joep
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Maxim S. Shatskih
Guest
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| Posted:
Sun Aug 21, 2005 8:15 am Post subject:
Re: Is there a rigorous definition for 'primary partition' ? |
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| Quote: | If I have two primary DOS partitions in the first PT sector (the MBR) and I
boot from a DOS floppy disk, how does DOS decide which of the PT entries
will get a drive letter?
|
Dunno. DOS is too old for me :)
I only know that all Windows NT warned about such partitioning scheme, that it
will be incompatible with DOS.
--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com |
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