Managing File Systems and Drives
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Archived content - No warranty is made as to technical accuracy. Content may contain URLs that were valid when originally published, but now link to sites or pages that no longer exist.
from Chapter 7, Windows NT Administrator's Pocket Consultant.
A hard drive is the most common storage device used on network workstations and servers. Users depend on hard drives to store their word-processing documents, spreadsheets, and other types of data. Drives are organized into file systems that users can access either locally or remotely:
Local file systems Local file systems are installed on a user's computer and don't require remote network connections to access. An example of a local file system is the C drive available on most workstations and servers. You access the C drive using the file path C:\.
Remote file systems Remote file systems, on the other hand, are accessed through a network connection to a remote resource. You can connect to a remote file system using the Map Network Drive feature of Microsoft Windows NT Explorer.
Wherever disk resources are located, it's your job as a system administrator to manage them. The tools and techniques you use to manage file systems and drives are discussed in this chapter. Chapter 8 looks at fault tolerance and drive arrays. Chapter 9 tells you how to manage files and directories.
Adding Hard Drives
Before you make a hard drive available to users, you'll need to configure it and consider the way it will be used. Windows NT makes it possible to configure hard drives in a variety of ways. The technique you choose depends primarily on the type of data you're working with and the needs of your network environment. For general user data stored on workstations, you may want to configure individual drives as stand-alone storage devices. In that case, user data is stored on a workstation's hard drive, where it can be accessed and stored locally.
Although storing data on a single drive is convenient, it isn't the most reliable way to store data. To improve reliability and performance, you may want a set of drives to work together. Windows NT supports drive sets and arrays using RAID (redundant array of inexpensive disk) technology, which is built into the operating system. RAID arrays are usually installed on Windows NT servers rather than on workstations.
Whether you use individual drives or drive sets, you'll need physical drives. Physical drives are the actual hardware devices that are used to store data. The amount of data a drive can store depends on its size and whether compression is used. Typical drives have capacities of 500 megabytes to 10 gigabytes. The two drive types most commonly used on Windows NT are
SCSI (small computer systems interface)
IDE (integrated drive electronics)
The terms SCSI and IDE are designators for the interface type used by the hard drives. This interface is used to communicate with a drive controller. SCSI drives use SCSI controllers. IDE drives use IDE controllers. In general, you'll find that SCSI drives are more expensive than IDE but offer more options and are faster.
With SCSI, you can connect up to seven drives to a single controller. Each drive connected to the primary controller is given a numeric designation from 0 to 6. This designation is the drive's SCSI ID, meaning drive 0 is SCSI ID 0, drive 1 is SCSI ID 1, and so on. The drive controller itself is usually designated as SCSI ID 7. Designators for drives on secondary controllers start where the first controller leaves off. For example, if the first controller has seven drives, the first drive on the second controller would normally be SCSI ID 8.
Generally, you set a drive's SCSI ID number before you install it. This is done by using the jumpers on the back of the drive. Instead of jumpers, some drives have a push button or similar mechanism for setting the SCSI ID. If you change the ID of a SCSI device, you must power cycle the drive. This ensures that the change takes effect.
SCSI devices are connected to the controller in a daisy chain, with each device serially in a single line. The first and last device in the chain must be terminated properly. Typically, the SCSI controller terminates the first device itself, and the last device in the chain uses an actual terminator.
Tip: If you're installing an additional SCSI-2 disk drive on a computer with SCSI devices, the system should already have a terminator. Simply remove the terminator from the existing drive, hook up the new drive, and then plug the terminator into the new drive to complete the chain.
Before you can use a hard drive, it must be low-level formatted. With SCSI, the manufacturer normally performs this task before shipping the drive. If you need to do a low-level format on site, you'll usually find that the manufacturer has supplied a utility for this purpose. If necessary, use this utility to format the drive.
With IDE, you can connect up to two drives to a controller. Each drive connected to the primary controller is given a numeric designation from 0 to 1. The first drive has a designator of 0. The second drive has a designator of 1. Designators for drives on secondary controllers start where the first controller leaves off. For example, if the first controller has two drives, the first drive on the second controller normally would have a designator of 3.
As with SCSI drives, you should set an IDE drive's designator before you install it. If this is the first IDE drive on a controller, you must set it up as the master device. If there are two drives on a controller, one drive must be set up as a master device and the other as a slave device. Generally, if you're installing a new drive, the existing drive becomes the master device and the new drive becomes the slave device.
Note: Generally, you can't perform a low-level format of an IDE drive. The manufacturer performs this task before shipping the drive.
Preparing a Drive for Use
Once you install a drive, you'll need to configure it for use. You configure the drive by partitioning it and creating file systems in the partitions as needed. A partition is a section of a physical drive that functions as if it were a separate unit. After you create a partition, you can create a file system in the partition.
The tool you'll use to configure drives is Disk Administrator. Disk Administrator makes it easy to work with the internal and external drives on a local system. To use it, you'll need to log on to the workstation or server you want to configure. Run Disk Administrator by going to Start, selecting Programs, then Administrative Tools, and then Disk Administrator. Disk Administrator has two main dialog box windows: Disk Configuration and Volumes.
The Disk Configuration Window
The Disk Administrator window shown in Figure 7-1, on the following page, provides an overview of all the drives installed on the system. In this example, there are three disk devices installed on the system: Disk 0, a fixed drive of 8056 MB, Disk 1, a zip drive, and a CD-ROM device. Drive 0 is further broken down into sections: a primary partition, three logical drives, and a section of free space. The information provided for these drive sections can tell you the following information:
Drive letter for the section
The text label for the section (known as a volume label)
The file system type, either FAT or NTFS
The size of the drive section in megabytesFigure 7-1: The Disk Administrator window shown here provides an overview of all the drives installed on the system.
Note: The first time you run Disk Administrator, the utility will display a dialog box telling you that the system configuration will be updated. Click OK. Windows NT is simply updating the system configuration information for your drives in Disk Administrator. You'll see the same dialog box anytime you install a new drive on the system and try to manage it with Disk Administrator.
More Detailed Drive Information
From the Disk Administrator window, you can get more detailed information on a drive section by right-clicking on it and then selecting Properties from the pop-up menu. Alternately, you can click on the drive section and then select the Properties button on the menu bar. When you do this, you'll see a dialog box much like the one shown in Figure 7-2. This is the same dialog box that you can access from Windows NT Explorer (by selecting the top-level folder for the drive and then choosing Properties from the File menu). The information provided on the General tab of the Properties dialog box tells you the following:
Drive letter for the section.
The text label for the section (known as a volume label).
The disk type. A local disk is a disk on the current computer system. A network drive is a disk located on a remote computer system that is accessible through a network connection. You may also see floppy, CD-ROM, and RAM drive types.
The file system type, either FAT or NTFS.Figure 7-2: The General tab of the Properties dialog box provides detailed information about a drive.
The amount of free space on the disk.
The amount of used space on the disk.
The total capacity of the disk.
The Volumes Window
Within Disk Administrator, you can also access a window that depicts volumes installed on the system. Click on the Volumes button on the menu bar or select Volumes from the View menu. As you can see from Figure 7-3, on the following page, the Volumes window provides a detailed summary of all the drives on the computer. Clicking on a column label, such as Name, allows you to sort the disk information based on that column. The column labels are used as follows:
Volume The drive letter of the volume
Name The text label (volume name)
Capacity The amount of data the volume can hold
Free Space The amount of free space in megabytes
% Free The amount of free space as a percentage of total drive capacity
Format The file system type, either FAT or NTFS
Fault Tolerant Whether the drive uses Windows NT fault tolerant features, such as mirroring or striping
Volume Type The type of volume used, such as a mirror set or stripe set
Fault Tolerant Overhead The total additional drive space required as a result of the fault tolerant feature used
Status The status of the volume, such as running or failed
Note Volume sets and fault tolerance are discussed in Chapter 8.Figure 7-3: In Disk Administrator, click on the Volume button or select Volume from the View menu to access the Volume window and get a detailed summary of all the drives on the computer.
Understanding Drive Partitions
Windows NT uses two types of partitions: primary and extended.
Primary partitions Drive sections that can be used directly for file storage. Each physical drive can have up to four primary partitions. You make a primary partition accessible to users by creating a file system on it.
Extended partitions Unlike primary partitions, these can't be accessed directly. Instead, extended partitions can be configured with one or more logical drives that are used to store files. Being able to divide extended partitions into logical drives allows you to divide a physical drive into more than four sections.
On Windows NT, a physical drive can have up to four primary partitions and up to one extended partition. This allows you to configure drives in one of two ways:
Using one to four primary partitions
Using one to three primary partitions and one extended partition
Note: With MS-DOS, a physical drive can have only one primary partition. This partition is the boot partition. If you plan to boot a Windows NT system in MS-DOS, you should use only one primary partition and then use an extended partition to create additional logical drives.
Assigning Drive Letters
After you partition a drive, you format the partitions to assign drive letters. This is a high-level format that creates the file system structure rather than a low-level format that sets the drive up for initial use.
You're probably very familiar with the C drive used by Windows NT. Well, the C drive is simply the designator for a disk partition. If you partition a disk into multiple sections, each section can have its own drive letter. You use the drive letters to access file systems in various partitions on a physical drive. Unlike MS-DOS, which assigns drive letters automatically starting with the letter C, Windows NT lets you specify drive letters. Generally, the drive letters C through Z are available for your use.
Note: The drive letter A is usually assigned to the system's floppy drive. If the system has a second floppy drive, the letter B is assigned to it, meaning you can only use the letters C through Z. Don't forget that CD-ROMs, Zip drives, and other types of media drives need drive letters as well.
The total number of drive letters you can use at one time is 24. This means you can have 24 active volumes on a single Windows NT system. If you need additional volumes, you can create them without assigning a drive letter. These volumes won't, however, be accessible until you assign them a drive letter.
Figure 7-4 shows the primary and extended partitions for a sample system in Disk Administrator. Disk 0 has two partitions: one primary partition and one extended partition. The primary partition is designated by the drive letter C. The extended partition is divided into three logical drives, which are designated with the drive letters D, E, and F. Disk 1 is a removable Zip drive. The third disk in the example is a CD-ROM drive, which also has a letter designator.
To help you differentiate between primary partitions and extended partitions with logical drives, Disk Administrator color-codes the partitions. For example, primary partitions may be color-coded with a dark-blue band and logical drives in extended partitions may be color-coded with a light-blue band. The key for the color scheme is shown at the bottom of the Disk Administrator window. You can change the colors by using the Colors dialog box that is displayed when you select Colors and Patterns from the Options menu.
Note: Before you work with Disk Administrator, there are several things you should know. If you create a partition but don't format it, the partition may be labeled as Unknown or Unformatted. If you haven't assigned a portion of the disk to a partition, this section of the disk is labeled Free Space. In Figure 7-4, both disk 0 and disk 1 have free space.
from Windows NT Administrator's Pocket Consultant by William R. Stanek. Copyright © 1999 Microsoft Corporation.