One thing that NFS does very well is recover from server failures.  All other 
file sharing protocols that I have seen tend to cause all the clients to fail 
when the server fails.  This feature is the main reason that NFS prevailed over 
other methods.  Recovering from a server failure was important in the early 80s 
when NFS was invented because servers would crash a couple of times a week.

-----Original Message-----
From: Linux on 390 Port [mailto:[EMAIL PROTECTED] Behalf Of
David Boyes
Sent: Thursday, April 10, 2008 11:37 AM
To: [email protected]
Subject: Re: Nfs and pcnfsd daemon


> > You don't run pcnfsd on the client; pcnfsd has to run on the server
> > side. It's a hack to allow non-Unix systems to authenticate a
connection
> > from a non-Unix system and get a valid numeric UID so that NFS
security
> > works.
> One of the major defects of the NFS protocol: Unix NFS daemons
> inexplicably believe whatever the client tells them.

Except for "secure" NFS, in which the tokens were just more complicated;
it still believed anything you told it; the questions were just harder
to understand...8-). The default behavior these days (ignore UID=0
requests unless deliberately stupidly configured) is at least somewhat
improved. 

NFS v4 just uses GSSAPI and defaults to Kerberos 5 authentication. Much
better, if considerably more complex to configure. 

As I said, NFS is a crummy protocol design. DNRFS on DECnet was a lot
smarter, as was Courier on XNS. But, it was lightweight and fit well in
EPROMs and didn't require licensing ...

> > You need to get the mountpw command (source is provided by IBM) and
run
> > it prior to trying to mount the filesystem on the Linux guest.
Mountpw
> > allows you to supply a VM userid and pw to authenticate the client,
> > which will then use the authentication token created by mountpw when
the
> > actual mount request comes in.
> Gaaack.  Are you saying that Linux doesn't support PCNFS as a client?

Well, pcnfsd was invented as a DOS thing -- DOS couldn't do the RPCs
necessary to support NFS and didn't have any concept of user anyway.
Linux has always had a full NFS client, so usually pcnfs isn't ever
needed. I can't say categorically that a pcnfsd client for Linux
*doesn't* exist, but I've never seen one. 

BTW: the URL I referenced is the IBM CMS NFS support page. If mountpw is
no longer required, probably time to update it. In your Copious Free
Time, that is... or make Miguel do it. It is All His Fault Now. 8-)

-- db

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