The case for the /usr merge [LWN.net]

The case for the /usr merge

Posted Jan 29, 2012 7:30 UTC (Sun) by raven667 (subscriber, #5198)
In reply to: The case for the /usr merge by lindi
Parent article: The case for the /usr merge

The simplest solution seems to be to manage the packages on the file server, just share out its /usr. Trying to manage packages on the client systems is folly for the reason you mentioned and probably others.

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The case for the /usr merge

Posted Jan 31, 2012 5:11 UTC (Tue) by rgmoore (✭ supporter ✭, #75) [Link] (4 responses)

That lets you manage the packages, but it doesn't fix the problem of packages that want to put files outside of /usr, especially into /etc. You'll need some way of getting any updated files from the server to the rest of the systems. Some of that is probably a sign that /etc needs a serious cleanup- there's a fair amount there that looks as if it belongs in /usr/share rather than /etc, and some of the other configuration stuff might be better done dynamically- but even with a well managed distribution there's going to be a need for updated files in /etc.

The case for the /usr merge

Posted Jan 31, 2012 7:22 UTC (Tue) by raven667 (subscriber, #5198) [Link] (1 responses)

The cases where there is a shared /usr implies a degree of sophisticated system administration already, probably capable of rolling out more complex changes if necessary when there is a platform update. That said, the common case is going to be patch deployment that should not require changes outside of /usr and for admins used to RHEL they won't expect intra platform upgrades anyway.

Actually thinking of RHEL I see a use case for virtualized servers where many OS instances share /usr but have private /var, /etc and /opt. That could provide great gains in memory and disk dedup for "free"

The case for the /usr merge

Posted Jan 31, 2012 19:35 UTC (Tue) by rgmoore (✭ supporter ✭, #75) [Link]

Actually thinking of RHEL I see a use case for virtualized servers where many OS instances share /usr but have private /var, /etc and /opt. That could provide great gains in memory and disk dedup for "free"

Virtualized machines is one of the use cases they mention specifically. The idea is that with all of the binaries and libraries pushed into /usr, / will shrink to something quite small and it will be easy to give every server its own copy without wasting much space. Cleaning up /etc would make management easier and save space for that kind of virtualization.

The case for the /usr merge

Posted Jan 31, 2012 13:17 UTC (Tue) by bluss (guest, #47454) [Link]

Maybe union-mounted /etc and /var?

The case for the /usr merge

Posted Feb 2, 2012 17:47 UTC (Thu) by jschrod (subscriber, #1646) [Link]

Environments that want to share /usr probably use tools like Chef or Puppet to control the content of /etc anyhow. At least, we do. ;-)

That said, there are really many files in /etc that are there for historical reasons and could go to /usr/share, IMHO.