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Date:      Wed, 6 May 2020 13:55:47 -0600
From:      Bob Proulx <bob@proulx.com>
To:        freebsd-questions@freebsd.org
Subject:   Re: redesignde the unix-like system directory
Message-ID:  <20200506134457056426360@bob.proulx.com>
In-Reply-To: <c3f5a607-760d-8a85-c0f3-e72ee6b9a3dc@tundraware.com>
References:  <83788746a7d8a802d8af4b582e00827166febd1a.camel@tom.com> <CAEJNuHzCcqR0-v_SEPT4QWai1owzL_41M-YN3fTS_YGHN0jwFg@mail.gmail.com> <9a387b42-8da5-2968-24ba-754c3e461252@kicp.uchicago.edu> <20200506151230.GI82984@trajan.stk.cx> <c3f5a607-760d-8a85-c0f3-e72ee6b9a3dc@tundraware.com>

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Tim Daneliuk wrote:
> Arne Steinkamm wrote:
> > >> /cloud, various cloud applications
> > >> /net,  network information and server information, etc.
> > Looking at a flat layout like this one gives me a feeling, that
> > most people forgot that it's a real bad idea to have a 
> > external mounted directory in the root directory... easy way to make
> > a system unresponsive in case of a network problem.
> 
> Can you say a bit more about why this is so?

Assume NFS for simplicity.  A mount point at the /nfsmount1 directory.
Then run "ls -l /".  That needs to stat(2) each entry in / and hits
/nfsmount1 with stat(2) which if the nfs server is not responding
cannot return an answer to the query.  A lot of daemons and cron jobs
will assume that the file system root and all entries in there are
available and will trigger this problem as a byproduct of their
operations.  I am just describing "ls -l" as the simplest way to
trigger the issue.  "NFS server not responding."  This can be a reason
for a system load of hundreds or thousands as process slots fill up
with stuck processes blocked waiting for I/O from an unresponsive server.

However in the proposal I think the entries I quoted were for use as a
subdirectory and not to have a mount point directly in root.

> > I keep the traditional filesystem layout

+1.  I prefer the traditional file system organization.

Bob



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