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OOM Killer, Lowmem issues. Recommended settings.

The problem is that system runs out of low memory. This is described in RedHat KB article DOC-52977 and ML notes 460141.1 and 842886.1.


Recommended system settings

Tune system settings to optimize low memory utilization.

vm.lower_zone_protection=100
vm.swappiness=80
vm.min_free_kbytes=19000
vm.dirty_expire_centisecs=2000
vm.dirty_writeback_centisecs=400
vm.vfs_cache_pressure=200

Recommended solution

For Oracle Database installation it is recommended to use 64bit OS


Getting crash dumps for Oracle VM's

Please edit the vm.cfg for the guest and have:

on_crash = 'coredump-restart'

This will then write a core dump to /var/xen/dump/ If there is insufficient space in /var then have the vm.cfg specify: "

on_crash = 'preserve'

You can then use the "xm dump-core" to dump the guest, specifying the dump location (e.g. an nfs mount).


OracleVM: Error: Acquire running lock failed: 256

Do at your own risk. I did it twice and both times it worked perfectly.

cd /OVS/.ovs-agent/db
mv vm.lock /tmp
mv vmp.lock /tmp
mv cluster.lock /tmp  

mv sr.lock /tmp
mv srvp.lock /tmp
mv srv.lock /tmp
mv ataskaux.lock /tmp


[root@trvovm01 db]# xm create //var/ovs/mount/2873C5736F264D84B5C0D8CB7815A218/running_pool/trvbrmmt05/vm.cfg
Using config file "//var/ovs/mount/2873C5736F264D84B5C0D8CB7815A218/running_pool/trvbrmmt05/vm.cfg".
Error: Acquire running lock failed: 256
[root@trvovm01 db]# /opt/ovs-agent-2.3/utils/do_rpc.py cluster_setup False
cluster_setup [False] =>
success
[root@trvovm01 db]# /opt/ovs-agent-2.3/utils/do_rpc.py cluster_setup
cluster_setup [] =>
success
[root@trvovm01 db]# xm create //var/ovs/mount/2873C5736F264D84B5C0D8CB7815A218/running_pool/trvbrmmt05/vm.cfg
Using config file "//var/ovs/mount/2873C5736F264D84B5C0D8CB7815A218/running_pool/trvbrmmt05/vm.cfg".
Started domain trvbrmmt05 (id=14)


CUPS: web access

# Restrict access to the server...
<Location />
  Order allow,deny
  Allow From 172.*
  Allow From 10.*
  Allow From 127.0.0.1
  AuthType None
</Location>

# Restrict access to the admin pages...
<Location /admin>
  Order allow,deny
  Allow From 172.*
  Allow From 10.*
  AuthType Basic
</Location>

Oracle Linux: Add public yum repo

cd /etc/yum.repos.d
wget http://public-yum.oracle.com/public-yum-el5.repo
vi public-yum-el5.repo

Enable only corresponding feeds


How to collect SAR report for today?

Use this to redirect data into text file:

[server1 ]# LC_ALL=C sar -A > /tmp/sar.data.txt