redesignde the unix-like system directory
Valeri Galtsev
galtsev at kicp.uchicago.edu
Wed May 6 20:19:25 UTC 2020
On 5/6/20 2:55 PM, Bob Proulx wrote:
> 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
Do people really do that? I kind of since forever use automounter or
similar, net mounts are in subdirectories of
/net
and - this is what _I_ do, not elegant thing, but convenient for my
users - I make directories in / named after names of cross mounted
machines, and put there symlinks to where automounter will mount
exported from these machines directories, like
/machine1name/data1 --> ../mnt/machine1name/data1
Never had trouble you describe, and nicety of automounter is "nothing
gets hang": once NFS server doesn't respond, mounts are unmounted
seamlessly by automounter. And are mounted again when someone tries to
access them and server is accessible.
Valeri
> 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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--
++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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