Primary partitions

Discussion in 'Windows 64bit' started by Kue2, Dec 1, 2009.

  1. Kue2

    Kue2 Guest

    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, Dec 1, 2009
    #1
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  2. 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?
    >
    >
    Bobby Johnson, Dec 1, 2009
    #2
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  3. 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
    John John - MVP, Dec 1, 2009
    #3
  4. Kue2

    R. C. White Guest

    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:...
    > 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, Dec 1, 2009
    #4
  5. Kue2

    Carlos Guest

    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?
    >
    >
    Carlos, Dec 1, 2009
    #5
  6. Kue2

    Kue2 Guest

    Thanks to All

    "Kue2" <> wrote in message
    news:...
    > 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, Dec 1, 2009
    #6
  7. 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?
    >>
    Richard Urban, Dec 2, 2009
    #7
  8. Kue2

    Tom Orle Guest

    "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=-
    Tom Orle, Dec 2, 2009
    #8
  9. 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.
    >
    John John - MVP, Dec 2, 2009
    #9
  10. Kue2

    Dave Warren Guest

    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.
    Dave Warren, Dec 2, 2009
    #10
  11. Dave Warren wrote:
    > 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,


    Well, in the interest of accuracy the extended partition is not a
    primary partition because it cannot be flagged active. By definition an
    active partition is one that can be marked active.

    > 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.


    It's not a BIOS limitation, the BIOS' role in all of this stops after it
    finds the first sector on the boot device and then hands over the boot
    process to the Master Boot Record. This is an MBR limitations on basic
    discs, or to be more precise (as posted by R. C. White) this is a
    limitation of the partition table.

    John
    John John - MVP, Dec 2, 2009
    #11
  12. Results of a Google for "more than 4 primary partitions" found @
    http://superuser.com/questions/5959...-primary-partitions-how-about-using-1-primary

    There are more alos.


    You can use more than 4 primary partitions, if you hide the extra
    partitions.

    For this game of hiding and unhiding partitions, you need a boot manager.
    Some Linux distributions replace the Windows boot manager with another
    that doesn't suffer from that limitation, although this should be
    undertaken with great precaution.

    The other way to go is to use a product that takes care of the whole
    thing. Some such products are :

    BootIt NG ($34.95)
    Support of over 200 primary partitions (if desired). I've used it and
    it's one of the best.

    GAG (initials, in spanish, of Graphical Boot Manager) (open-source)
    Allows boot of up to 9 different operating systems installed in primary
    and extended partitions. Never used it.

    Partition Commander 11 ($49.95)
    No info on maximum partitions number. I've used it a long time ago and
    it worked then pretty well.

    Norton PartitionMagic 8.0 ($69.95)
    Otherwise called BootMagic, no info on maximum partitions number, and
    seems to only support partitions up to 300GB. Never used it, and I
    usually stay away from Norton products.

    Warning: Before playing with partitions, take great care with your backups.


    Richard Urban wrote:
    > Please enlighten me on this! Other software that allows more than 4
    > primary partitions on a single hard drive.
    >
    Bobby Johnson, Dec 2, 2009
    #12
  13. Bobby Johnson wrote:
    > Results of a Google for "more than 4 primary partitions" found @
    > http://superuser.com/questions/5959...-primary-partitions-how-about-using-1-primary
    >
    >
    > There are more alos.
    >
    >
    > You can use more than 4 primary partitions, if you hide the extra
    > partitions.


    That is not correct, a hidden partition still holds one of the four
    entries in the partition table, the only difference is that the
    "partition type" bit in its entry is changed to hide the partition. A
    basic MBR disk *cannot* have more than four partitions, one of which can
    be an extended partition holding logical drives. You must resort to
    third party boot managers if you want to create more than 4 primary
    partitions.

    John
    John John - MVP, Dec 2, 2009
    #13
  14. Kue2

    R. C. White Guest

    Hi, Tom.

    You got me! ;^{ Thanks for the catch.

    In the WinXP RK (pp. 1210-1216), there is a good bit of detail about "Disk
    Sectors on MBR Disks". It includes a picture of a Partition Table (Figure
    27.5) and its Fields (27.6) and System ID Values (27.7).

    The first byte of the table is the Boot Indicator and can be only 80
    (bootable) or 00 (not bootable). The 5th byte is the System ID, which can
    have one of 16 different values; 0x05 means Extended partition.

    The same information is online at
    http://technet.microsoft.com/en-us/library/bb457122.aspx , but it has been
    re-organized. You'll have to scroll way down on that page to Table 28-7,
    Partition Table Fields, and thereabouts. In the 2nd edition of the WinXP RK
    it starts on p. 1189 (Chapter 26). Recent (post WinXP) Resource Kits seem
    to have LESS detail about these topics and more about exotic topics (GPT
    disks, etc.) that don't interest me (yet).

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

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

    "Tom Orle" <> wrote in message
    news:...
    > "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=-
    R. C. White, Dec 2, 2009
    #14
  15. Kue2

    Bill Guest

    "Norton PartitionMagic 8.0 ($69.95)
    Otherwise called BootMagic, no info on maximum partitions number, and
    seems to only support partitions up to 300GB. Never used it, and I
    usually stay away from Norton products."

    Supports 4 primary partitions. I have created partitions greater than 300GB
    with Partition Magic, but have done no further manipulation with them after
    creation. Was developed by PowerQuest, not Norton. Symantec bought out
    PowerQuest and discontinued any further development of Partition/Boot Magic
    other than rebranding, therefore I do not consider it a Symantec product. I
    believe (memory is fuzzy here) Symantec bought PowerQuest solely to stop
    PowerQuests Drive Image competition with Ghost and to obtain PowerQuest
    patents. The technology used in Drive Image, which was far superior in my
    opinion, was later brought into Ghost. However, it appears Symantec had no
    interest in further development of Partition Magic/Boot Magic.

    I continue to use (PowerQuest version 8.01) to create partitions and as my
    boot manager. After partitions are created, I then format the partition
    with the OS installation disk being installed, especially with Vista and
    Win7. My BootMagic resides on a MSDOS 6.22 first primary partition.
    Advanced partition hiding is enabled to isolate OS partitions from each
    other.
    --
    ______________
    BullDawg
    Associate Expert
    In God We Trust
    ______________

    "Bobby Johnson" <> wrote in message
    news:...
    > Results of a Google for "more than 4 primary partitions" found @
    > http://superuser.com/questions/5959...-primary-partitions-how-about-using-1-primary
    >
    > There are more alos.
    >
    >
    > You can use more than 4 primary partitions, if you hide the extra
    > partitions.
    >
    > For this game of hiding and unhiding partitions, you need a boot manager.
    > Some Linux distributions replace the Windows boot manager with another
    > that doesn't suffer from that limitation, although this should be
    > undertaken with great precaution.
    >
    > The other way to go is to use a product that takes care of the whole
    > thing. Some such products are :
    >
    > BootIt NG ($34.95)
    > Support of over 200 primary partitions (if desired). I've used it and it's
    > one of the best.
    >
    > GAG (initials, in spanish, of Graphical Boot Manager) (open-source)
    > Allows boot of up to 9 different operating systems installed in primary
    > and extended partitions. Never used it.
    >
    > Partition Commander 11 ($49.95)
    > No info on maximum partitions number. I've used it a long time ago and it
    > worked then pretty well.
    >
    > Norton PartitionMagic 8.0 ($69.95)
    > Otherwise called BootMagic, no info on maximum partitions number, and
    > seems to only support partitions up to 300GB. Never used it, and I usually
    > stay away from Norton products.
    >
    > Warning: Before playing with partitions, take great care with your
    > backups.
    >
    >
    > Richard Urban wrote:
    >> Please enlighten me on this! Other software that allows more than 4
    >> primary partitions on a single hard drive.
    >>
    Bill, Dec 5, 2009
    #15
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