sample-11 - 830 CASE STUDY 2: WINDOWS 2000 CHAP. 11 11.7...

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830 CASE STUDY 2: WINDOWS 2000 CHAP. 11 11.7 THE WINDOWS 2000 FILE SYSTEM Windows 2000 supports several file systems, the most important of which are FAT-16 , FAT-32 , and NTFS ( NT File System ). FAT-16 is the old MS-DOS file system. It uses 16-bit disk addresses, which limits it to disk partitions no larger than 2 GB. FAT-32 uses 32-bit disk addresses and supports disk partitions up to 2 TB. NTFS is a new file system developed specifically for Windows NT and car- ried over to Windows 2000. It uses 64-bit disk addresses and can (theoretically) support disk partitions up to 2 64 bytes, although other considerations limit it to smaller sizes. Windows 2000 also supports read-only file systems for CD-ROMs and DVDs. It is possible (even common) to have the same running system have access to multiple file system types available at the same time. In this chapter we will treat the NTFS file system because it is a modern file system unencumbered by the need to be fully compatible with the MS-DOS file system, which was based on the CP/M file system designed for 8-inch floppy disks more than 20 years ago. Times have changed and 8-inch floppy disks are not quite state of the art any more. Neither are their file systems. Also, NTFS differs both in user interface and implementation in a number of ways from the UNIX file system, which makes it a good second example to study. NTFS is a large and complex system and space limitations prevent us from covering all of its features, but the material presented below should give a reasonable impression of it. 11.7.1 Fundamental Concepts Individual file names in NTFS are limited to 255 characters; full paths are limited to 32,767 characters. File names are in Unicode, allowing people in coun- tries not using the Latin alphabet (e.g., Greece, Japan, India, Russia, and Israel) to write file names in their native language. For example, φιλε is a perfectly legal file name. NTFS fully supports case sensitive names (so foo is different from Foo and FOO ). Unfortunately, the Win32 API does not fully support case-sensitivity for file names and not at all for directory names, so this advantage is lost to pro- grams restricted to using Win32 (e.g., for Windows 98 compatibility). An NTFS file is not just a linear sequence of bytes, as FAT-32 and UNIX files are. Instead, a file consists of multiple attributes, each of which is represented by a stream of bytes. Most files have a few short streams, such as the name of the file and its 64-bit object ID, plus one long (unnamed) stream with the data. How- ever, a file can also have two or more (long) data streams as well. Each stream has a name consisting of the file name, a colon, and the stream name, as in foo:stream1 . Each stream has its own size and is lockable independently of all the other streams. The idea of multiple streams in a file was borrowed from the Apple Macintosh, in which files have two streams, the data fork and the resource fork. This concept was incorporated into NTFS to allow an NTFS server be able
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SEC. 11.7 THE WINDOWS 2000 FILE SYSTEM 831 to serve Macintosh clients.
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This note was uploaded on 05/20/2011 for the course COP 4600 taught by Professor Yavuz-kahveci during the Spring '07 term at University of Florida.

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sample-11 - 830 CASE STUDY 2: WINDOWS 2000 CHAP. 11 11.7...

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