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 Unionfs Underlying ext2 filesystem Image- installation script Loop- mounted Device Image un-installation script X X

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 >  System accommodates up to 1000 devices comfortably.  A typical system could have between software packages 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