Message-ID: <46EAF2F2.2020006@ora-600.net>
Date: Fri, 14 Sep 2007 13:45:38 -0700
From: Jeremiah Wilton <jeremiah@ora-600.net>
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To:  don@seiler.us
CC: "Elliott, Patrick" <patrick.elliott@medtronic.com>, 
 oracle-l <oracle-l@freelists.org>
Subject: Re: Weird database hanging
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Reply-to: jeremiah@ora-600.net

Don,

Do you have any reason to believe that your system exceeded these limits 
during your issue?  I am certain that reaching this limit would not have 
caused PMON and process creation timeouts such as those you saw.  Unix 
returns an error, and does not hang, when the resource limit is reached. 
  For instance, your login as SYSDBA would have failed, not hung and 
eventually succeeded.

I believe this is a red herring, and in fact another shot in the dark. 
You could easily reach a limit like this during a hang, since inbound 
requests would require additional sessions to be started, but that's not 
a root cause, it is a result.

In fact, by increasing limits like this, you could easily make such 
hanging situations worse, by allowing incoming requests to completely 
swamp the host with no checks until over 16000 processes are spawned. I 
don't think that is what you want.  We shouldn't set values based on 
what "experts" tell us, but rather to the correct value for the system 
in question based on business and technical needs.

Again, I recommend finding out where all that time was going on the 
instance when PMON was timing out.  ASH is your friend.

Jeremiah Wilton
ORA-600 Consulting
http://www.ora-600.net

Don Seiler wrote:
> oracle ~ $ ulimit -u
> 2047
> oracle ~ $ ulimit -n
> 1024
> 
> This is a big gaffe.  According to Puschitz those values should be set
> in the .bash_profile to 16384 and 63536, respectively.  Mea culpa on
> completely missing these in the setup.

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