informix hang when nfs server is down

informix hang when nfs server is down

Post by Simon Dav » Sat, 13 Nov 1993 03:53:43

>> >I am running SE 5.0 on an IBM RS/6000 AIX 3.2 (call it dbmach).  There is a
>> >user on the same system who nfs mounts a directory onto his home directory
>> >on dbmach (/u/johndoe).  We'll call the other machine he is mounting
>> >from johnsmach.  Informix is installed in /usr/informix and the database is
>> >in /usr/informix/db/mydb.dbs.
>This is a trace while I performed the mention commands.  Some irrelevant lines
>have been removed.  This is not a trace when the NFS server was hung, but one
>in which informix started ok.  The directories /u/sam, /u/johndoe, and /u/jane
>are not in any of my PATH variables or any of my environment variables.  So
>why is informix being so nosey.  Why is it looking in directories not related
>to it.

I suspect that it is doing a call to getcwd(), or similar to find out the current
working directory.  The algorithm for this generally involves odd searching of
./.. paths.  EG on a Sun, a trace of /bin/pwd gives:

open ("/usr/lib/", 0, 04000000021) = 3
open ("/dev/zero", 0, 07) = 4
open ("/etc/", 0, 0) = 3
open ("/usr/openwin/lib", 0, 01010525) = 3
open ("/usr/lib/", 0, 022230) = 3
open ("/usr/lib/", 0, 022250) = 3
open ("./../", 0, 035736104630) = 3
open ("./../../", 0, 0) = 3
open ("./../../../", 0, 0) = 3
open ("./../../../../", 0, 0) = 3
open ("/etc/mtab", 0, 0666) = 4

It is the O/S implementation of getcwd() that is the cause, your trace shows that
it may be over doing things though.



1. Informix hangs when NFS

|When an NFS server dies with a mounted filesystem, informix hangs, on
|aix at least, even when the filesystem that is down is un-related in
|any way to the informix application running. It does not exist in
|any paths, there is NO relationship between this filesystem and the

|WHY? Are there any work arounds?

What do you mean by Informix 'hanging' ?  We have had problems on
HP-UX when using NFS (In some cases the whole machine was hanging),
but I believe we applied some operating system patches that fixed it.

Perhaps you can try checking for AIX patches related to NFS/LAN - are
you using I-Star and if so, does the host machine hang as well as the
clients ?


Richard Ridley
DHL Asia Pacific

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