NFS server not responding prevents boot

Chuck Lever cel at
Fri May 19 07:04:21 PDT 2006

Sergey Babkin wrote:
>> From: Steven Hartland <killing at>
>>> Anyway the big question is how can I change all our NFS
>>> mounts so that failed mounts dont prevent the machines
>>> booting to the point where they can be fixed remotely
>>> i.e. have started sshd.
>> Doh!! spent ages googling for the answer then found it
>> in 2mins of looking through the man pages.
>> The option for anyone interested is "bg" for -b from
>> the command line to mount:
>> [quote="man mount_nfs"]
>> -b 
>> If an initial attempt to contact the server fails, fork off a
> I usually use "soft,bg". The "soft" option makes the
> operations on this filesystem fail if the server
> is not available instead of hanging (unkillable!)
> forever and waiting for the server to come up.

"soft" is usually a bad idea if you care about data integrity.  It can 
cause all kinds of silent data corruption.  Even on read-only mounts, a 
soft timeout can cause clients to corrupt their own caches.

If you absolutely must use "soft", then also use NFS over TCP, and use a 
long retransmit timeout (like 60 seconds) and enable the dumb timer (the 
"-d") option.  That's about the safest way to use "soft".

corporate:	cel at netapp dot com
personal:	chucklever at bigfoot dot com

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