Software Installation Using Disk Images

By: Irena Lanc and Peter Sempolinski

Software Installation Conventional methods of software installation

involve: Downloading the package Unpacking Compiling Managing path and environment variables

This leads to package files being strewn in directories across disk.

How can this system be made more efficient?

Our Idea Create a disk image of the software package,

and mount it as a loop device.

Virtual File System

Loop- mounted Device

Loop-mounted Device

Unionfs

Underlying ext2 filesystem

Image-installation

script

Loop- mounted Device

Image un-

installationscript

Loop-mounted Device

XX

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Basic Working Prototype

Number of loop devices hard-limited in kernel Possible to ask for more devices at boot time. However,

this greatly slows down the boot sequence when number of devices > 4000.

System accommodates up to 1000 devices comfortably. A typical system could have between 1000-2000

software packages

Complications

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Loop Devices vs Boot Time

Number of Loop Devices

Boot

tim

e (

s)

Complications Dependencies

Images created using files from debian packages, but since we’re re-packaging, dependencies not automatically fetched.

Further tools needed to manage dependencies.

Unionfs Demands careful coordination of merges by the script. As yet untested in scalability when merging hundreds of

packages.

Road Ahead 1. Add more scripts to manage dependencies,

and generally make system easier to use.

2. Create a test bed to obtain metrics such as program install time, memory/processor usage, and scalability.

3. Kernel hacking To get more out of Unionfs/loopback devices, certain

aspects could be modified to provide more flexibility and better performance