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Q138364: Windows NT Partitioning Rules During Setup

Article: Q138364
Product(s): Microsoft Windows NT
Version(s): 2000,3.1,3.5,3.51,4.0
Operating System(s): 
Keyword(s): 
Last Modified: 08-AUG-2001

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The information in this article applies to:

- Microsoft Windows NT Server versions 3.1, 3.5, 3.51, 4.0 
- Microsoft Windows NT Workstation versions 3.1, 3.5, 3.51, 4.0 
- Microsoft Windows NT Advanced Server, version 3.1 
- Microsoft BackOffice Small Business Server 
- Microsoft Windows 2000 Advanced Server 
- Microsoft Windows 2000 Server 
- Microsoft Windows 2000 Professional 
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SUMMARY
=======

During the installation of Windows NT, Setup determines the best partitioning
scheme to use based on the existing partition table entries and where you choose
to install Windows NT. Windows NT Setup restraints restrict the boot partition
of up to 4 GB. The limit may be smaller depending on disk geometry. The actual
value that is used as the limit is whatever Setup believes to be 1024 cylinders
worth of disk space. Sometimes this is 1 GB, 2 GB, or 4 GB, but can be some
other value depending on the make, model, and configuration of the hard disk
adapter in use. This is the amount of space with which the text-mode portion of
the installation can work. From this amount, you can create partitions that do
not exceed 4 GB because the partition must first be formatted FAT and this file
system has a limit to 4 GB.

For additional information, please see the following articles in the Microsoft
Knowledge Base:

  Q119497 Boot Partition Created During Setup Limited to 4 Gigabytes

  Q224526 Windows NT 4.0 Supports Maximum of 7.8-GB System Partition

These articles explains rules you should consider before installing Windows NT on
computers that contain large hardware RAID-5 drive arrays if you want to use the
full contiguous capacity of these large arrays after Windows NT is installed.

MORE INFORMATION
================

When you use a Hardware RAID-5 configuration, it is very important to understand
how Windows NT partitions your drive during Setup in order to maintain maximum
contiguous capacity of the large Array for user data after Windows NT is
installed. Setup follows these rules:

Rule 1
------

If no partitions pre-exist on the drive, Setup makes the primary partition the
size you specify for Windows NT (up to 4GB).

Rule 2
------

If a primary partition already exists, and you choose to install Windows NT in an
unformatted free space, you are prompted for the size of the partition to create
(up to 4 GB). After you choose the partition size, Setup creates the largest
extended partition possible (up to 7.8 GB if using a 63 sectors/track, 255
tracks/cylinder translation scheme) and creates a logical drive within the
extended partition of the size you choose. After Windows NT is installed, the
unused extended partition space can be used for additional logical drives.

Rule 3
------

If a primary and extended partition already exist and free space in the extended
partition is selected, Windows NT creates a new logical drive of the size
specified by you.

Rule 4
------

If a primary and extended partition already exist and free space is available and
selected outside of the extended partition, Windows NT creates another primary
partition of the size the you choose (up to 4GB) for Windows NT to be installed
in.

There are two possible workarounds:

- Prior to installing Windows NT, use MS-DOS FDISK to create an extended
  partition of 250 MB, then create a logical drive of 250 MB within the
  extended partition. When you install Windows NT, select this partition as the
  target to install Windows NT in.

  -or-

- Install Windows NT into the first primary MS-DOS FAT partition. After Windows
  NT is installed, run Disk Administrator and create a second primary partition
  of 250 MB. Re-install Windows NT into this second primary partition and then
  delete the first Windows NT installation from the first primary MS-DOS
  partition.

EXAMPLE
-------

You have four 2-GB drives configured in a hardware RAID-5 configuration for a
total capacity of 6 GB and want a 5.5-GB NTFS partition for user data after
Windows NT is installed. You have MS-DOS pre-installed on a 250-MB primary
partition prior to installing Windows NT and want to keep this intact. You
decide to install Windows NT into a separate NTFS partition and create a 250-MB
partition from free space during Windows NT Setup.

Using rule 3 above, Windows NT creates an extended partition of 4 GB, then
creates a 250-MB logical drive within to install Windows NT on. After Windows NT
is installed, Disk Administrator shows the following:

  C:   250   MB FAT
  D:   250   MB NTFS (logical drive)
     3.750   GB extended partition space (free)
     1.750   GB Free space
     -----
     6.0     GB total usable space in hardware raid-5 configuration.

The problem is that the 2 free spaces cannot be combined to equal the 5.5-GB
partition space wanted for user data.


Additional query words: smallbiz

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Keywords          :  
Technology        : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT351search kbWinNT350search kbWinNT400search kbWinNTW350 kbWinNTW350search kbWinNTW351search kbWinNTW351 kbwin2000AdvServ kbwin2000AdvServSearch kbwin2000Serv kbWinNTW310 kbWinNTSsearch kbWinNTS400search kbWinNTS400 kbWinNTS351 kbWinNTS350 kbWinNTS310 kbWinNTAdvSerSearch kbWinNTAdvServ310 kbwin2000ServSearch kbwin2000Search kbwin2000ProSearch kbwin2000Pro kbWinNTS351search kbWinNTS350search kbWinNTS310search kbAudDeveloper kbWinNT310Search kbWinNTW310Search kbSBServSearch kbWinAdvServSearch
Version           : :2000,3.1,3.5,3.51,4.0
Issue type        : kbinfo

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