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    SubjectRe: NFS hang + umount -f: better behaviour requested.
    >>>>> "Peter" == Peter Staubach <staubach@redhat.com> writes:

    Peter> John Stoffel wrote:
    Robin> I'm bringing this up again (I know it's been mentioned here
    Robin> before) because I had been told that NFS support had gotten
    Robin> better in Linux recently, so I have been (for my $dayjob)
    Robin> testing the behaviour of NFS (autofs NFS, specifically) under
    Robin> Linux with hard,intr and using iptables to simulate a hang.
    >>
    >> So why are you mouting with hard,intr semantics? At my current
    >> SysAdmin job, we mount everything (solaris included) with 'soft,intr'
    >> and it works well. If an NFS server goes down, clients don't hang for
    >> large periods of time.

    Peter> Wow! That's _really_ a bad idea. NFS READ operations which
    Peter> timeout can lead to executables which mysteriously fail, file
    Peter> corruption, etc. NFS WRITE operations which fail may or may
    Peter> not lead to file corruption.

    Peter> Anything writable should _always_ be mounted "hard" for safety
    Peter> purposes. Readonly mounted file systems _may_ be mounted
    Peter> "soft", depending upon what is located on them.

    Not in my experience. We use NetApps as our backing NFS servers, so
    maybe my experience isn't totally relevant. But with a mix of Linux
    and Solaris clients, we've never had problems with soft,intr on our
    NFS clients.

    We also don't see file corruption, mysterious executables failing to
    run, etc.

    Now maybe those issues are raised when you have a Linux NFS server
    with Solaris clients. But in my book, reliable NFS servers are key,
    and if they are reliable, 'soft,intr' works just fine.

    Now maybe if we had NFS exported directories everywhere, and stuff
    cross mounted all over the place with autofs, then we might change our
    minds.

    In any case, I don't dis-agree with the fundamental request to make
    the NFS client code on Linux easier to work with. I bet Trond (who
    works at NetApp) will have something to say on this issue.


    John
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