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Chapter 4
The Disk And File Systems
- • Modifying The Disk Administrator Display
- • Creating And Preparing A Partition/Volume
- • Assigning Drive Letters
- • Creating A Volume Set
- • Extending A Volume Or Volume Set
- • Creating A Mirror Set
- • Breaking A Mirror Set
- • Creating A Stripe Set
- • Creating A Stripe Set With Parity
- • Setting And Viewing File And Folder Permissions
- • Copying And Moving Folders Or Files
- • Creating A New Folder
- • Taking Ownership Of Folders And Files
- • Configuring Auditing On Folders And Files
- • Compressing Volumes, Folders, And Files
- • Disabling The 8.3 Short File Name Creation
Administrator’s Notes...
The disk subsystem can be defined as encompassing the necessary hardware and software components to implement a robust file system. In this chapter, the hardware components are discussed in generic terms as adhering to the design goals of Windows NT, and our discussion will remain hardware-independent. In addition, the fault-tolerance issues discussed are based on the standard software functions of Windows NT and are not reliant on hardware-based, fault-tolerant solutions.
The Disk Subsystem
The disk subsystem is controlled by the I/O Manager, which controls all input and output requests for Windows NT. The I/O Manager is a component of the NT Executive, which acts as the interface between the high- and low-level components of the operating system—in other words, between the kernel (low) and the Win32 subsystem (high).
The I/O Manager consists of a series of layered drivers that communicate with each other via the Executive I/O Manager, as shown in Figure 4.1. For example, for the file system driver to communicate with a disk drive, an I/O request would have to be routed via the I/O Manager. The I/O Manager, in turn, communicates with the disk driver and the disk controller. Because the I/O Manager is used to pass I/O requests between the drivers, each driver is kept as a self-contained module, making it easy to replace, remove, or add a driver without affecting the entire operating system.
Figure 4.1 The I/O Manager and layered drivers.
A good analogy for the way the I/O Manager and drivers interact is an elevator in an office block. To move from one floor to the next, employees have to use the elevator. If a particular floor is closed, the elevator still delivers the other employees to their required locations, and the organization as a whole continues to function. If you substitute I/O requests for employees, drivers for floors, and the I/O Manager for the elevator, you end up with a pretty good idea of how the disk subsystem works.
The Disk Administrator
The disk subsystem is managed with the Disk Administrator, which is a graphical system management tool accessed via the Administrative Tools menu. The Disk Administrator can be used to perform the following tasks:
- • Create and delete partitions
- • Create, delete, format, label, and extend volumes and volume sets
- • Create and delete stripe sets
- • Assign drive IDs
- • Save and restore the drive configuration
In addition, with Windows NT Server, the Disk Administrator can do the following:
- • Establish and break disk mirroring or duplexing
- • Create, delete, and regenerate stripe sets with parity
To use the Disk Administrator, you need to be a member of the Administrator group. When you invoke the Disk Administrator for the first time, a signature is written to disk 0. This signature does not overwrite any data and is used internally by Windows NT.
Disk Administrator provides two views of the disk configuration: partition view, shown in Figure 4.2, and volume view, shown in Figure 4.3.
Figure 4.2 The Disk Administrator partition view.
Figure 4.3 The Disk Administrator volume view.
To use the Disk Administrator effectively, you need to have an understanding of both the terminology and underlying technology, which is explained in the following section.
Windows NT Workstation And Server
The following terms apply to technology and features common to both the Server and Workstation versions of Windows NT:
- • System and boot partitions—Under Windows NT, the system partition is the volume that contains the files required to load Windows NT. This must be on the disk that is accessed by the computer system on startup. On x86-based systems, this partition must be marked as active. The boot partition contains the Windows NT operating system files. This partition can be the same partition as the system partition, but it doesn’t have to be. RISC-based systems do not use an active partition to boot, but instead have a hardware-based boot configuration.
- • Primary partition—A partition that can be marked as active and could be used to load an operating system. There can be a maximum of four primary partitions per physical disk.
- • Extended partition—This is used to subdivide free disk space into smaller logical areas. There can be only one extended partition per disk.
- • Volume— An area of disk that is partitioned and formatted for any of the Windows NT-supported file systems.
- • Volume sets—Disk partitions joined together into a single logical area. The partitions can be on the same or different physical disks and can include disks of different types. There can be up to 32 separate areas of disk joined together to form a single volume set. The data is written to volume sets in a sequential fashion, i.e., one area of the volume set is filled up before moving on to the next. The system and boot partitions cannot be part of a volume set.
Note: Both volumes and volume sets can be extended in size without reformatting the volume, as long as the volume is formatted for use by NTFS. If the volume you wish to extend is formatted for FAT use, you must first convert it to NTFS and then extend it. The conversion from FAT to NTFS is a one-way process.
- • Stripe sets—In a stripe set, data is written across different physical disks in 64 K stripes on partitions of equal size, as shown in Figure 4.4. This technique is often used to increase the disk I/O performance; because the I/O load is spread over a number of disk spindles, I/O throughput is increased. Stripe sets can be configured over 2 through 32 physical disks. Disk striping provides no fault tolerance. If any of the disk drives containing a stripe fails, all data in that stripe set will be lost.
Figure 4.4 Stripe sets.
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