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CS 3210 Operating System Design
Fall 2005 — Hutto
Georgia Tech, College of Computing
Homework 2
DUE: Final Project Demo Time (by Saturday 17 December 2005)
Topics Covered:
•
VFS
•
IO Devices
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Disk Caches, Implementing Read/Write
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Ext2/Ext3, Journaling
Work individually on this. Please prepare printed solutions using the word processing software of
your choice to the following questions (no handwritten solutions accepted) and bring to your final
project. Questions amplify material from the lectures and the assigned readings. Questions
frequently require you to investigate Linux or OS features and capabilities. Please make use of all
available resources (web, man pages, kernel source, discussions with staff, etc.).
The questions on this homework are more exploratory so you probably need to write about one
page for each question to answer them properly. Have fun and good luck!
1. Linux has supported a Logical Volume Manager (LVM) for some time. (LVMs were developed in
commercial operating systems originally. The first Linux LVM was inspired by a similar product from
HP.) Learn about LVMs and describe the major features that they support. Then *briefly* describe
how an LVM might be implemented in Linux based on your knowledge of the VFS layer, ext2, the
block device subsystem and block device management. Your answer to this question should be about
a page and a half of text.
2. FAST is the yearly USENIX File and Storage Technology conference. The conference
proceedings are made public one year after each conference and are a good place to learn about
interesting new filesystem technologies. In the 2004 proceedings, the following paper by a bunch of
CMU students won Best Paper Award:
A Framework for Building Unobtrusive Disk Maintenance Applications
Thereska, Schindler, Bucy, Salmon, Lumb, and Ganger
Carnegie Mellon University
http://www.usenix.org/events/fast04/tech/thereska.html
In this paper they discuss how applications can utilize “idle” disk time and blocks for useful
purposes (rather like having the idle process implement some useful function.) Briefly sketch how you
could use this idea in Linux Ext2 to implement a background disk defragmenter (also known as a
“repacker” or “cleaner”).
3. FUSE (Filesystem in USEr Space) is an interesting capability that has been recently implemented
in Linux. It allows simple filesystems to be written entirely in user-space with very little effort.
Read about FUSE on the web and explain, in your own words, how it is implemented in Linux.
