Low FD limit a performance issue?
- From: Herring Dave - dherri <Dave.Herring@xxxxxxxxxx>
- To: oracle-l List <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 2 Nov 2011 13:49:45 +0000
I did a crazy thing the other day - reviewed an alert log from a system I
inherited a while ago. I found that after a recent auto-restart a message was
displayed: "WARNING:Oracle instance running on a system with low open file
descriptor limit. Tune your system to increase this limit to avoid severe
performance degradation.". Sure enough, on this system /etc/init.d/init.crsd
has the line "ulimit -n unlimited" in it, which on RHEL 4 generates an error,
so the FD limit defaults to 1024 (bug 5862719).
The problem is easy to resolve but my question is on Oracle's warning. How
could a low open file descriptor limit be a potential source of "severe
performance degradation"? Isn't it a black-or-white issue, either the limit is
high enough or if not, the db won't open/you can't add more datafiles?
DAVID HERRING
DBA
Acxiom Corporation
EML dave.herring@xxxxxxxxxx
TEL 630.944.4762
MBL 630.430.5988
1501 Opus Pl, Downers Grove, IL 60515, USA
WWW.ACXIOM.COM
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