v14stanford.edu-Directories_and_Links

v14stanford.edu-Directories_and_Links - Directories and...

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http://w w w .stanford.edu/~ouster/cgi-bin/cs140-w inter12/lecture.php?topic=directories January 11, 2012 Directories and Links Directories and Links Lecture Notes for CS 140 Winter 2012 John Ousterhout Readings for this topic from Operating System Concepts : Section 11.3. Naming: how do users refer to their files? How does OS find file, given name? First step: file descriptor has to be stored on disk, so it will persist across system reboots. Early UNIX versions: all descriptors stored in a fixed- size array on disk. Originally entire descriptor array was at the outer edge of the disk. Result: long seeks between descriptors and file data. Later improvements: Place descriptor array mid-way across disk. Many small descriptor arrays spread across disk, so descriptors can be near to file data. Space for descriptors is fixed when the disk is initialized, and can't be changed. Unix/Linux terms: File descriptor is called an i-node Index of i-node in the descriptor array: i-number . Internally the OS uses the i-number as
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This note was uploaded on 04/02/2012 for the course CS 140 taught by Professor Rosenblum during the Winter '08 term at Stanford.

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v14stanford.edu-Directories_and_Links - Directories and...

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