On Fri, 21 Dec 2012 11:24:45 +0100 "J. Roeleveld" <jo...@antarean.org> wrote:
> On Friday, December 21, 2012 09:57:25 AM Michał Górny wrote: > > Just let me know when you have to maintain a lot of such systemd > > and upgrade, say, glibc. Then maybe you'll understand. > > A shared /usr means I need to update ALL the systems at once. > When /usr is not shared, I can update groups at a time. Yes, and this is what disqualifies it for the general case. If you can't update one at some point, you can't update the others or it is going to likely get broken in a random manner. > To save time, a shared filesystem containing binary packages can easily be > used and this is what I use myself. > I have one VM that is used to rebuild the packages when I want to do an > update > and the real host then simply uses the binary packages. > The configuration items needed for emerge are synchronized between the build > system and the actual server. Wait, wait. So you have introduced even more hackery to get it working? Good to hear. That's really a good reason to support your arguments. 'I got it working with a lot of hackery, so it is a good solution!' > The main reason why I would never share an OS filesystem between multiple > systems is to avoid the situation where a failed upgrade takes down the > entire > environment. And this doesn't happen in your case because...? Because as far as I can see: 1) failed upgrade in /usr takes down the entire environment, 2) failed upgrade in / may take down the machine, 3) failed hackery you're doing to get it all working may have even more unpredictable results. And yes, I prefer to take down the entire environment and fix it in one step. That sounds much better than trying to get it back up and re-sync all the machines which got into some mid-broken state. > And a shared OS filesystem also introduces a very nice Single Point of > Failure. What will happen when the NFS-server (or whatever is used) goes down > for whatever reason? And what is the difference now? Is it another argument like 'hey, i can still see the command-line, so it's better. not that i can do anything useful with it.' > In other words, to make an environment that has a very nice single point of > failure possible, existing working environments are classed as "broken". NFS-shared system does classify as 'a single point of failure'. -- Best regards, Michał Górny
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