diskless_clients

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Subject: Re: --excludepath installation 
From: Michael Redinger <Michael.Redinger@uibk.ac.at>
Date: Mon, 8 May 2000 22:00:33 +0200 (MET DST)




> > Yes, but that's really a pain ... I even found it more convenient keeping
> > /etc and /var in memory (ramdisk) ...
> 
> Warning to others: don't put /var in RAM unles syou know what you're 
> doing; even then there's probably a better way. Many programs store stuff 
> in /var that you don't want to lose next time you boot.
> 
> Nothing should be writing to /etc; anything that does can probably be 
> fixed with a symlink to a convenient place in /var.


Yeah, completely right ... you have to be extremely careful about that. I
did this with some scripts for those clients that needed it (however, most
of them were "real" client - no server stuff. Eg. syslog is done to a 
syslog server etc. ...
Building clients with absolutely no harddisk or any other place where to 
store permantent data is possible if the "client" is not a "server" 
(I did this - and as I did not recieve any message that said
something different I suppose I'm right ... ;) ).

Concerning "even then there's probably a better way ... " : suppose you
cannot use a bootrom (there are various technical reasons for this), do not
want any client to store things on your hard disk using NFS (which is a 
security concern - NFS is very insecure) - eg. if you have untrusted
users on your network. Well, then there aren't many other possibilities
if you don't want to use the local hard disk.) However - you should 
definitely know what you are doing ...


> > > Remember that /etc has to be kept in step with /usr - for example, if you 
> > > upgrade sendmail to 8.10, then everyone has to reconfigure it at the same 
> > > time. Even if sendmail 8.10 works with 8.9 config files (they do look 
> > > pretty similar) you can be sure some things will not.
> > > 
> > > If you control it on one machine, then you can cut individuals over to the 
> > > updated /usr as you get their /etc fixed up. Assuming you have a 
> > > mistake-proof way of doing it;-)
> > 
> > 
> > Well, that's why rpm is so nice ... install them on the central system 
> > (only /usr). Then make the clients update it too (autorpm ; excluding /usr).
> > If you really install everything (the machines have the same set of rpms,
> > so no dependeny problems should occur) autorpm is rather save ...
> 
> I don't see just why your approach is better than exporting the whole 
> shebang, with special provision for /var and /etc.
> 
> You CAN maintain an old (preupdate) tree to export and a new tree. Next 
> reboot gets the new tree - you've changed /etc/fstab to point to the new 
> one.
> 
> However, it's done, /etc needs host-by-host care. Possibly this can be doe 
> with a script; I don't expect there are many complex differences, it's 
> mostly a matter of hostname and such. You'd need to do something like 
> format your disk, install and setup
> 
> I've just eyeballed /etc on my RHL 6.1 system:
> rpm -Va | grep \ /etc
> There are 55 files that show as not being as distributed; of those most 
> arise from changes from installing other software (/etc/services) or from 
> changes likely to be site-wide (/etc/printcap). Only a few are likely to 
> differ between hosts. I imagine this could readily be fixed by a script 
> run before init (see initrd) which takes the global /etc and copies it to 
> local disk or ramdisk and fixes it.
> 
> syslogd should be logging to a different host; there are times when you 
> need a record of what someone did; mail sent, possible unauthorised use 
> etc.
> 
> 
> It seems to me this is no more difficult to set up (and probably more 
> certain) than seting up & using autorpm.

(this is something similar to what St

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