Primary partitions

Say I have four hard drives(physical drives) in one computer.

Is the four primary partition per each physical hard drive?

In theory than I could have 16 primary partitions in a computer that

has four physical drives. Is this statement correct?

With Microsoft's partitioning that's correct. There are other utilities
that will let you do more than four primary partitions.

If your installing Win 7 let it do the partitioning. Win 7 has a 100MB
partition for system files and then another primary partition for the
rest of Win 7. Win 7, as does Vista, you can shrink that larger
partition after installation is done.

Kue2 wrote:
> Say I have four hard drives(physical drives) in one computer.
>
> Is the four primary partition per each physical hard drive?
>
> In theory than I could have 16 primary partitions in a computer that
>
> has four physical drives. Is this statement correct?
>
>

Kue2 wrote:
> Say I have four hard drives(physical drives) in one computer.
>
> Is the four primary partition per each physical hard drive?
>
> In theory than I could have 16 primary partitions in a computer that
>
> has four physical drives. Is this statement correct?

Yes.

John

Hi, Hugh.

Yes.

Each HDD has a Partition Table in the first physical sector on that DISK.
THAT Partition Table applies to - and ONLY to - THAT particular piece of
hardware. If you have 4 physical disks, then you have 4 partition tables.

Each Partition Table is exactly 64 bytes long. That is room for exactly 4
entries of exactly 16 bytes each. So on 4 physical disks, you have 4
partition tables with a maximum of 4 possible partitions each, for a total
of 16 primary partitions in that system.

In EACH partition table, ONE of the partitions may be designated as an
EXTENDED partition. This extended partition cannot be assigned a "drive"
letter. But one or more "logical drives" may be created within the extended
partition, and each of those logical drives may be separately formatted and
assigned a "drive" letter. The only practical limit to the number of
logical drives in an extended partition is the space available in the
partition. So you could have 3 primary partitions plus an extended
partition divided into 6 logical drives for a total of 9 "drives" on that
one physical HDD. Plus other "drives" on the other 3 HDDs.

Since each entry in a partition table is only 16 bytes, there is only so
much information that can be crammed into those 16 bytes. Briefly, this is
code for the partition's beginning and ending sectors on the disk, the file
system (NTFS, FAT32, etc.), sector size, and a single bit that indicates
whether this is an extended partition OR if this is the currently Active
(bootable) partition on that HDD.

Microsoft Press publishes a Resource Kit (RK) for each version of Windows;
this RK is a book of many pages (1699 pages for the WinXP RK) and a hefty
price (USD59.99). About half the book is aimed at administrators of large
systems, but the other half is very useful for even a one-man one-computer
user like me. Among other information in the RK is the contents of such
things as boot sectors and MBRs and details of the setup and startup
processes. Well worth spending the money and investing the time if you
expect to be involved with computers for very long.

RC
--
R. C. White, CPA
San Marcos, TX

Microsoft Windows MVP
Windows Live Mail 2009 (14.0.8089.0726) in Win7 Ultimate x64

"Kue2" <> wrote in message
news:0B8E4471-BC06-4180-A3A5-...
> Say I have four hard drives(physical drives) in one computer.
>
> Is the four primary partition per each physical hard drive?
>
> In theory than I could have 16 primary partitions in a computer that
>
> has four physical drives. Is this statement correct?

Hugh,
If you have time to spare, take a look here:
http://en.kioskea.net/contents/repar/partitio.php3
Carlos

"Kue2" wrote:

> Say I have four hard drives(physical drives) in one computer.
>
> Is the four primary partition per each physical hard drive?
>
> In theory than I could have 16 primary partitions in a computer that
>
> has four physical drives. Is this statement correct?
>
>

Thanks to All

"Kue2" <> wrote in message
news:0B8E4471-BC06-4180-A3A5-...
> Say I have four hard drives(physical drives) in one computer.
>
> Is the four primary partition per each physical hard drive?
>
> In theory than I could have 16 primary partitions in a computer that
>
> has four physical drives. Is this statement correct?
>
>

Please enlighten me on this! Other software that allows more than 4 primary
partitions on a single hard drive.

--

Richard Urban
Microsoft MVP
Windows Desktop Experience & Security


"Bobby Johnson" <> wrote in message
news:...
> With Microsoft's partitioning that's correct. There are other utilities
> that will let you do more than four primary partitions.
>
> If your installing Win 7 let it do the partitioning. Win 7 has a 100MB
> partition for system files and then another primary partition for the rest
> of Win 7. Win 7, as does Vista, you can shrink that larger partition
> after installation is done.
>
> Kue2 wrote:
>> Say I have four hard drives(physical drives) in one computer.
>>
>> Is the four primary partition per each physical hard drive?
>>
>> In theory than I could have 16 primary partitions in a computer that
>>
>> has four physical drives. Is this statement correct?
>>

"R. C. White" <> wrote:

> ... and a single bit that indicates
>whether this is an extended partition OR if this is the currently Active
>(bootable) partition on that HDD.

RC,

How can this single bit specify 3 types of partitions?
Bootable primary (active)
Non-bootable primary (is such a partition possible?)
Extended

Is there another bit signifying an active partition ... or do all
primary partitions have to be active?

Just curious ...

-=tom=-

These partitioning utilities create a small partition for their own use
and they then change the IPL code to point to this special partition
which holds an alternate partition table. As mentioned in another post
the 'real' partition table on a basic MBR disc can only hold 4 entries,
by storing the partition information in a partition of its own the boot
manager can create and handle more than 4 primary partitions. This is
basically the same way that the extended partition works, it allows you
to create more than 4 partitions by storing the table for the logical
drives in the extended partition instead of the partition table. Of
course logical drives cannot be active but boot managers have their own
code and methods to allow the partitions that they manage to be active.
You should *never* use the Windows Disk Management tool to do any disk
work if you use these third party boot managers, the Windows Disk
Manager relies on the partition table (or the LDM database for Dynamic
volumes) and it will not recognize partitions created by third party
boot managers which use an alternate partition table.

John

Richard Urban wrote:
> Please enlighten me on this! Other software that allows more than 4
> primary partitions on a single hard drive.
>

In message <> Bobby Johnson
<> was claimed to have wrote:

>With Microsoft's partitioning that's correct. There are other utilities
>that will let you do more than four primary partitions.

With all due respect, four is a hard limit here.

You can create an extended partition (which is actually a primary
partition itself) and multiple logical partitions within that, but the
limitation of four primary partitions has nothing to do with Windows,
it's a holdover from the original IBM BIOS implementation of ages past.