oracle 10g RAC 节点重启，但是没有记录有效的日志信息--问题诊断

oracle 10g RAC 重启，但是没有记录有效的日志信息

from:
Oracle? Database Release Notes
10g Release 2 (10.2) for Linux x86-64
B15666-19
____________________________________________________________________
6.15 Configuring Oracle Clusterware Process Monitor Daemon

The 10.2.0.4 patch release for Oracle Clusterware on Linux includes

the Oracle Clusterware Process Monitor Daemon (oprocd). It is started

automatically by Oracle Clusterware to detect system hangs. When it

detects a system hang, it restarts the hung node.

Review the following configuration information if you have installed

the 10.2.0.4 patch set.

Oracle has found wide variations in scheduling latencies observed

across operating systems and versions of operating systems. Because

of these scheduling latencies, the default values for oprocd can be

overly sensitive, particularly under heavy system load, resulting in

unnecessary oprocd-initiated restarts (false restarts).

Oracle recommends that you address scheduling latencies with your

operating system vendor to reduce or eliminate them as much as

possible, as they can cause other problems.

To overcome these scheduling latencies, Oracle recommends that you

set the Oracle Clusterware parameter diagwait to the value 13. This

setting increases the time for failed nodes to flush final trace

files, which helps to debug the cause of a node failure. You must

shut down the cluster to change the diagwait setting. However, if you

prefer, you can use the default timing threshold for diagwait. In

that case, you do not need to perform the procedure documented here.

If you require more aggressive failover times to meet more stringent

service level requirements, then you should open a service request

with Oracle Support to receive advice about how to tune for lower

failover settings.

Note:
Changing the diagwait parameter requires a clusterwide shutdown. Oracle recommends that you change the diagwait setting either immediately after the initial installation, or during a scheduled outage.

Log in as root, and run the following command on all nodes, where

CRS_home is the home directory of the Oracle Clusterware

installation:

# CRS_home/bin/crsctl stop crs
Enter the following command, where CRS_home is the Oracle Clusterware

home:

# CRS_home/bin/oprocd stop
Repeat this command on all nodes.

From one node of the cluster, change the value of the diagwait

parameter to 13 seconds by issuing the following command as root:

# CRS_home/bin/crsctl set css diagwait 13 -force
Restart the Oracle Clusterware by running the following command on

all nodes:

# CRS_home/bin/crsctl start crs
Run the following command to ensure that Oracle Clusterware is

functioning properly:

# CRS_home/bin/crsctl check crs

来自IBM的解释：
Server running AIX with Oracle RAC reboots itself

Technote (troubleshooting)

Problem(Abstract)
Server running AIX with Oracle RAC reboots itself with no warning

Symptom
AIX server shuts down and/or reboots.

A REBOOT_ID is logged in /var/adm/ras/errlog indicating "SYSTEM

SHUTDOWN BY USER" although no shutdown or reboot command was issued

by any user.

example error message...

LABEL: REBOOT_ID
IDENTIFIER: 2BFA76F6

Date/Time: Wed Dec 3 08:19:09 2008
Sequence Number: 1447
Machine Id: 0000ABCD1234
Node Id: nodeA
Class: S
Type: TEMP
Resource Name: SYSPROC

Description
SYSTEM SHUTDOWN BY USER

Probable Causes
SYSTEM SHUTDOWN

Detail Data
USER ID
0
0=SOFT IPL 1=HALT 2=TIME REBOOT
0
TIME TO REBOOT (FOR TIMED REBOOT ONLY)
0

Cause
Oracle Real Application Clusters (RAC) is known to reboot the

operating system with no warning due to configuration of the oprocd

daemon

Environment
AIX with Oracle RAC

Diagnosing the problem
Oracle Real Application Clusters (RAC) typically runs a process called oprocd.

The idea of OPROCD is quite straightforward. It’s goal is to provide

I/O fencing. Basically oprocd works by setting a timer, then

sleeping. If, when it wakes up again and gets scheduled onto cpu, it

sees that a longer time has passed than the acceptable margin, oprocd

will decide to reboot the node.

You can check for the oprocd process with the ps command...

# ps -ef | grep oprocd
root 221672 1 0 08:27:44 - 0:00
/u01/crs/oracle/product/10.2.0/crs_1/bin/oprocd run -t 1000 -m 500 -f

These options to oprocd are saying -t 1000 (wake up every 1000 ms)

and -m 500 (allow up to 500 ms margin of error on the time that

oprocd wakes up before rebooting). In other words, if oprocd wakes up

after > 1.5 secs it’s going to force a reboot.

 

Resolving the problem
The timeout and margin times are computed from the elements of

diagwait and reboot time and it isn't recommended changing them via

the init.cssd file, but rather through the command 'crsctl set css

diagwait <secs>'.

There is a formula involved in the calculation of the times. For

example, if the reboot time is 3 and you submit a diagwait setting of

13 you will get -t 1000 -m 10000.

# crsctl set css diagwait 13 -force

# ps -ef | grep oprocd
root 221672 1 0 08:27:44 - 0:00
/u01/crs/oracle/product/10.2.0/crs_1/bin/oprocd run -t 1000 -m 10000

-f

You can see that the margin has changed to 10000 ms, that is 10

seconds in place of the default 0.5 seconds. This is a 20 fold

increase allows oprocd more time to determine if the node needs to be

rebooted.

IBM recommends the customer contact Oracle Support before modifying

this value.

IBM and Oracle came to the agreement that a diagwait value of 13 is a

suitable value if the best practices are used...

 

http://w3-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP101513 

IBM recommends customers follow best practices, and if possible

update to AIX 6.1 or AIX 7.1 with current Technology Levels which

include the new non-pagable kernel as the preferred corrective

action.

The Oracle master document can be found here... http://www.oracle.com/technetwork/database/clusterware/overview/rac-aix-system-stability-131022.pdf

ADDENDUM:

The following Oracle document provides additional information on the

cssdagent process which is related to oprocd...

http://docs.oracle.com/cd/E14072_01/rac.112/e10717/intro.htm 
The cssdagent process monitors the cluster and provides I/O fencing.

This service formerly was provided by Oracle Process Monitor Daemon

(oprocd), also known as OraFenceService on Windows. A cssdagent

failure results in Oracle Clusterware restarting the node.

root 11010182 1 0 18:43:40 - 0:05

/GDICMP/oracle/cloud/product/11.2/bin/cssdagent

===

Additional Oracle processes which are known to reboot AIX include the

following which will appear in ps -ef output...

octssd.bin reboot
ohasd.bin reboot
crsd.bin reboot

 

 

Cross reference information  Segment Product Component Platform

Version Edition
Operating Systems AIX family  AIX 5.2, 5.3, 6.1 

 

Document information
AIX family

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Software version:
Version Independent

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Operating system(s):
AIX

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Reference #:
T1011228

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Modified date:
2011-10-19
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