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Windows NT Server

Windows NT Boot Sequence Files

NTLDR This hidden, read-only system file loads the operating system. (system partition root)

BOOT.INI This is a read-only system file, used to build the Boot Loader Operating System Selection menu on Intel x86-based computers. (system partion root)

BOOTSECT.DOS - This is a hidden system file loaded by NTLDR if another operating system, such as MS-DOS, Windows 95, or O/S 2 version 1.x, is selected instead of Windows NT. This file contains the boot sector that was on the hard disk before installing Windows NT. (system partition root)

NTDETECT.COM - Hidden, read-only system file used to examine the hardware available and to build a hardware list. This information is passed back to NTLDR to be added to the registry later in the boot process.(system partition root)

NTBOOTDD.SYS - Hidden, read-only, system file is only on systems that boot from a SCSI hard disk and on which the BIOS on the SCSI adapter is disabled. This driver accesses devices attached to the SCSI adapter during the Windows NT boot sequence. (system partition roo)

Ntoskrnl.exe and Hal.dll (system root\system32)

System (system root\system32\config)

Device drivers (system root\system32\drivers)

RISC Boot Sequence Files

OSLOADER.EXE - This is the operating system loader (equivalent to NTLDR on Intel x86-based computers).

*.PAL (Alpha only). These files contain PAL code, software subroutines that provide an operating system with direct control of the processor.

Common Boot Sequence Files

NTOSKRNL.EXE - This is the Windows NT kernel file, located in the systemroot\system32 folder.

SYSTEM - This file is a collection of system configuration settings. The file is in the systemroot\System32\Config folder. It controls which device drivers and services are loaded during the initialization process.

DEVICE DRIVERS - These are files that support various device drivers, such as Ftdisk and Scsidisk.

Boot Sequence

Ntldr switches the processor from real mode into 32-bit flat memory mode. Ntldr, as is the case with any 32-bit code, requires this 32-bit flat memory mode before it can carry out any functions.

Ntldr starts the appropriate mini-file system drivers. Mini-file system drivers are built into Ntldr to find and load Windows NT from different file system formats.

If there is a Boot.ini, Ntldr reads it and displays the operating system selections contained within the Boot.ini file. This is called the Boot Loader Operating System Selection menu.

Ntldr loads the operating system. The operating system that is loaded is the one selected by the user or, if no selection is made, the default operating system.

If Windows NT is selected, Ntldr runs Ntdetect.com. Ntdetect.com scans the hardware and then sends the list of detected hardware back to Ntldr for later inclusion in the registry under HKEY_LOCAL_MACHINE\HARDWARE

Ntldr then loads Ntoskrnl.exe, Hal.dll, and the System hive. Ntldr scans the system hives and loads the device drivers configured to start at boot time. Finally, Ntldr starts Ntoskrnl.exe, at which point the boot process ends and the load phases begin.

Kernel Load Phase

The Kernel load phase begins as soon as Ntoskrnl.exe is loaded. The hardware abstraction layer (HAL), which hides platform-specific hardware issues from Windows NT, is loaded after the kernel.

* It is possible to display the names of the drivers being loaded on the screen by adding an "/sos" switch to the appropriate operating system line in Boot.ini.

Kernel Initialization Phase

In this stage of the boot sequence, the screen is painted blue. The kernel initialization phase initialize the kernel and the drivers that were loaded during the kernel load phase.

Last Known Good configuration

When to use it:

You install a new device driver, restart Windows NT, and the system stops responding. The Last Known Good control set enables you to start Windows NT because it does not contain any reference to the new, faulty driver.

You install a new video driver and are able to restart the system. However, you cannot see anything, because the new video resolution is incompatible with your video adapter. Do not try to log on. If you have the optioni to shut down the computer without logging on, do so. If that option is not available, you need to restart your computer by turning it off or using the reset button. Wait for all disk activity to stop before you initiate the restart, especially if the computer has FAT volumes.

You accidentally disable a critical device driver (such as the SCSIport driver). Windows NT is not able to start and automatically reverts to the Last Known Good control set.

When not to use it:

Any problem that is unrelated to changes in control set information, such as problems arising from incorrectly configured user profiles or incorrect file permissions.

After you logged on after making changes. Here, the Last Known Good control set has already been updated to include the changes.

Switching between different hardware profiles, such as docked and undocked laptops. The Last Known Good control set is only a method to switch between configuration information in the registry.

Startup failures caused by hardware failures or missing or corrupted files.

Emergency Repair

If Windows NT fails to boot or function correctly, and using the Last Known Good configuration does not solve the problem, you can use the Emergency Repair process in Windows NT Setup to restore Windows NT.

Because the Update Repair Info option deletes and creates files under systemroot\repair, if Windows NT is installed on an NTFS partition, the user performing the update must have the appropriate permissions to the folder.
TheEmergency Repair Disk utility (rdisk) does not back up the Default, SAM, and Security files, which contain the user accounts and file security, unless you specify the /s parameter with the rdisk command at the command prompt.
If your system becomes corrupt and you cannot repair it using the Emergency Repair Disk or using the information in the Repair folder, you must reinstall Windows NT from the original installation source.

Windows NT Server in the Enterprise

The Enterprise Environment

Unlike a simple computing environment, which typically contains one or more servers in a single domain and a single location, an enterprise environment can expand to multiple servers in multiple domains and locations.

Windows NT Server Directory Services provide several key advantages:

Support single network login ID and password to gain access to all shared domain resources.
Manage resources and accounts from a centralized location.
Implement services to update network account and security information.
Maintain user accounts and passwords in diverse environments.
Incorporate BackOffice Directory Services such as authentication management and single

Trust Relationships

Domain can be linked to each other by establishing a trust relationship. A trust relatioinship is a secure communication link between two domains. With a trust relationship, a domain can accept user accounts created in other domains as valid accounts and allow those accounts to use local resources.

RAID (Redundant Array of Inexpensive Disks)

Windows NT Server implements disk fault tolerance with Redundant Array of Inexpensive Disks (RAID) technology. RAID allows data being streamed to the disk drives by the Windows NT disk subsystem to be divided up among several physical disks. Individual data files are written to more than one disk in a manner that, depending on the RAID level used, can improve performance or reliability.

RAID Levels

RAID Level 0 is really not a fault tolerant system because there is no redundancy; RAID 0 is disk striping only. When data is written to a RAID 0 logical device, the data is broken up and distributed to several devices. This makes the write process more efficient because the data is being written to several devices simultaneously, but no parity information is created, and there is no redundancy.

RAID Level 1, also known as mirroring or duplexing, allows all data written to one disk to also be written to another disk. This provides fault tolerance but requires twice the disk space needed to support the system. If a system requires 500 MB of disk space, RAID Level 1 requires 1000 MB because everything is stored twice.

RAID Level 2-4 are not supported by Windows NT Server.

RAID Level 5, takes parity information and spreads it across the data disks. This way, if one fails, the remaining disks contain parity information necessary to rebuild the disk without interrupting service to the operating system.

Advantages of disk striping with parity include:

Best performance for read operations.
Highest degree of fault tolerance.
A single disk failure doesn't make the server inoperable.

Disadvantages of disk striping with parity include:

Write operations require three times the amount of memory because of parity calculations.
When a disk fails, performance is severely degraded.

Minimum NT Server Requirements

Intel 486/33 or greater, or Digital Alpha AXP class processor

16 MB RAM

Intel 125 MB , RISC 160 MB of HD space

Database Size Calculation

Account Type Disk Space Requirement

User Account 1.0 KB

Computer Account 0.5 KB

Global Group Account 0.5 KB + 12 bytes per member

Local Group Account 0.5 KB + 36 bytes per member

To calculate the amount of space used by group accounts, use the following formula:

Bytes Used by Local Groups = (# of Local Group X 512)+(# of Member X 36)

Bytes Used by Global Groups = (# of Local Group X 512)+(# of Member X 12)

Number of Domain Controllers

One domain controller is suggested for every 2000 users. However, 3000 users in one domain could require three domain controllers: two domain controllers are needed to handle 3000 user validation requests, and one domain controller is needed for redundancy. If there were only two domain controllers, and one were to go down, a single domain controller would have to service

Number of domain controllers necessary in a single domain

Number of Users Number of BDC Servers (no redundancy)

10 - 2000 1

5000 3

10,000 5

20,000 10

30,000 15

Browser Election

A browser election occurs when a Windows NT domain controller system starts, a preferred master browser comes online, or a computer cannot locate a master browser. A computer initiates an election by sending a special datagram called an election datagram includes election criteria that all browsers will compare against their own. If the browser has better election criteria than the sender of the election datagram, the browser will issue its own election datagram and enter what is called an election-in-progress state. If the browser does not have better election criteria than the sender of the election datagram, the browser attempts to determine which system is the new master browser.