Primary and Extended Partition ?

[Mark]

I am new to XP and someone have told me that there are maximum 4 primary
partitions OR 3 primary partitions + any number of extended partitions no
matter how many HD I have.

I would like to know
1) What is the difference between Primary and Extended Partitions ?
2) If it is just for boot up, we can have 1 Primary Partitions + any number
of Extended Partitions. Why do we bother to have more than 1 Primary
Partitions ? There must be some advantage of Primary Partition than
Extended Partition ?
3) Does Linux System also support the same number of Primary and Extended
Partitions as XP ? If YES, which factor determines the number of primary
and extended partitions ? Is it the HD ?

Thanks

 

[Pegasus]

See below.

I am new to XP and someone have told me that there are maximum 4 primary
partitions OR 3 primary partitions + any number of extended partitions no
matter how many HD I have.

This is only partly correct. Each disk can have up to four primary
partitions, or three primary and one extended partition. The extended
partition can have any number of logical drives.

I would like to know
1) What is the difference between Primary and Extended Partitions ?

Primary partitions are bootable, logical drives are not (except
with some third party boot loaders).

2) If it is just for boot up, we can have 1 Primary Partitions + any number
of Extended Partitions. Why do we bother to have more than 1 Primary
Partitions ? There must be some advantage of Primary Partition than
Extended Partition ?

Most home PCs use one single primary partitions. Many professional
installations use two partitions:
- One primary partition (for Windows & Programs)
- A further partition for data
This division is useful for a number of reasons.

3) Does Linux System also support the same number of Primary and Extended
Partitions as XP ? If YES, which factor determines the number of primary
and extended partitions ? Is it the HD ?

Ask a Linux newsgroup.

 

[Tim Slattery]

I am new to XP and someone have told me that there are maximum 4 primary
partitions OR 3 primary partitions + any number of extended partitions no
matter how many HD I have.

I would like to know
1) What is the difference between Primary and Extended Partitions ?

One of the very first sectors on a hard disk will contain a partition
table. The specification for a partition table hasn't changed since
hard drives for PCs were first being built and were, by today's
standards, tiny.

The partition table has four slots. Each defines a partition by
telling where on the disk it starts, where it ends, a flag indicating
whether the partition is "active", and a *very* terse descriptor
that's supposed to give some idea of what kind of partition it is.

A partition can be primary or extended, and there can be no more than
one extended partition on a disk. One of the first items in an
Extended partition is - another partition table. This one can be
larger than four entries (I don't know whether there's a limit). The
things it defines can't be partitions, since they are within a
partition, so they're called "Logical Drives".

I believe that only primary partitions can be bootable.

More detailed information on partition tables is here:
http://www.ata-atapi.com/hiwtab.htm

 

[nil_einne1]

Another advantage of primary partitions is they're simple to work with
with partition editing tools. For example, PM is able to merge
partitions but you cannot of course merge a logical drive with a
primary partition very easily. Similarly, if you have free space to the
left or right of a partition, you can increase the size of the
partition easily with most tools but it's not always so easy with
logical drives. You will usually need to increase the size of the
extended partition first then the logical drive and not all tools even
handle this well. Same goes for decreasing the size of course. I'm sure
there are other potential problems when working with logical drives.

Personally, I will stay away from extended partitions and logical
drives unless you really need more then 5 partitions which is only
likely if you have several OSes on one drive or at least one OS which
likes a lot of partitions e.g. Linux.

 

[Ken Blake, MVP]

I am new to XP and someone have told me that there are maximum 4
primary partitions OR 3 primary partitions + any number of extended
partitions no matter how many HD I have.

No, this isn't correct. First of all, it has nothing to do with Windows XP.
It's the same in XP as it's been in previous versions of DOS/Windows.

Second, the limits are per physical drive, not "no matter how many HD
[you]."have

Third, the limit is four partitions, total (primary plus extended), per
drive

I would like to know
1) What is the difference between Primary and Extended Partitions ?

You can only boot from a primary partition, not an extended one (at least
not without special boot control software).

2) If it is just for boot up, we can have 1 Primary Partitions + any
number of Extended Partitions.

No. It's four partitions total. An extended partition can contain any number
of logical drives. Logical drives are often loosely called "partitions,"
since they get a drive letter and look like partitions when you use them
within DOS or Windows, but technically they are not really partitions.

Why do we bother to have more than 1
Primary Partitions ? There must be some advantage of Primary
Partition than Extended Partition ?

They are for booting multiple operating systems.

3) Does Linux System also support the same number of Primary and
Extended Partitions as XP ? If YES, which factor determines the
number of primary and extended partitions ? Is it the HD ?

Sorry, I know nothing about Linux. I'll leave this question for others.

 

[Jonny]

An extended partition is considered a primary partition as part of the 4
primary partition limit.
An extended partition is a container for logical partitions.
An extended partition does not contain a file system, so you can't store
files in it.
Logical partitions within an extended partition can easily number beyond the
primary partition limit, and are not part of the 4 primary limitation rule.
If you only use XP, there's no point is having more than one extended
partition.
This is not a Linux newsgroup..