[clug] UnionFS based package management system: good idea or fatally flawed?

[steve jenkin]

In my wild, erratic stumble across the deserts & jungles of the
InterWebs, came across this yesterday on the LFS, Linux From Scratch site.

This approach is how "Plan 9" might do things, and a nice wrinkle could
be using ISO images, squashfs or crypto-signed blobs to house 'units of
change'. Solves some problems, creates others.

There's a question I had and STFW'd, but couldn't find a good answer...

 - How big is the performance hit (and RAM needed?) for an Overlay/Union
mount.

 - Normal systems need to support ~5,000 packages, could this approach
scale?

cheers
steve

[In "Plan 9", there's a single /bin and /lib. You overlay mount
everything you need onto them.]


<http://www.linuxfromscratch.org/hints/downloads/files/pkg_unionfs.txt>

AUTHOR: Samad Lotia

DATE: 2008-10-21

SYNOPSIS: A UnionFS-based package management system

DESCRIPTION:
  UnionFS ... allows one to merge the contents of many disparate
directories so they all appear as a single directory.
This functionality provides a basis for a minimal, yet effective,
package manager.
This approach appeals to those who want a more rational  and organized
directory structure.

HINT.

This type of package management is inspired by GoboLinux's unique take
on the archaic Unix directory structures*. Instead of installing all
packages into the /usr directory whose contents can become quite
unwieldy, packages are installed into their own directories.

-- 
Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin