[lug] NSLU2

[David L. Anselmi]

Bear Giles wrote:
[...]
> Perhaps someone can clarify something for me.  I thought that Samba and 
> NFS can't coexist.  I mean, obviously, you can run both servers at the 
> same time.  But you can't export the same files with both Samba and 
> NFS.   (Or mod_dav, god forbid.)
[...]
> The problem is caching and locking.

I think the kernel probably supports what's needed, but this is an 
application decision and the apps can value responsiveness over 
integrity.  Here's a page with some info (just a quick check, I don't 
know how current it is):

http://www.samba.org/samba/docs/man/Samba-HOWTO-Collection/locking.html

So that reminds me of a question.  At work on Solaris 8, if we use cp to 
update a library used by a running app the app will crash.  So we're 
told to make sure we use rdist.  How does Linux handle this and is there 
a better way?

The difference is that cp opens the file and overwrites the contents 
while rdist unlinks the file and links to the new file.  With cp, 
running apps will see the changes as they are executing (edit a running 
bash script with vi and see what happens).  With rdist, running apps 
keep their references and are oblivious to the new files until they are 
restarted (or do a new open, which is usually ok).

The thing is that I'm not aware of Linux packages doing any special 
handling to prevent problems when upgrading.  They may stop network 
servers first, and restart them after.  But libc gets upgraded 
regardless that KDE, mozilla, and whatever are running during the 
upgrade.  I guess I'm not completely sure what happens with rpms or 
debs, but make install usually just copies things.

Anyone know the details of this or do I have to do my own research?

Thanks!
Dave