Troubleshooting 11.2 Clusterware Node Evictions (Reboots) [ID 1050693.1]

Troubleshooting 11.2 Clusterware Node Evictions (Reboots) [ID 1050693.1]
	Modified 29-JUL-2010Type BULLETINStatus PUBLISHED

In this Document
Purpose
Scope and Application
Troubleshooting 11.2 Clusterware Node Evictions (Reboots)
NODE EVICTION OVERVIEW
1.0 - PROCESS ROLES FOR REBOOTS
2.0 - DETERMINING WHICH PROCESS IS RESPONSIBLE FOR A REBOOT
3.0 - TROUBLESHOOTING OCSSD EVICTIONS
3.1 - COMMON CAUSES OF OCSSD EVICTIONS
3.2 - FILES TO REVIEW AND GATHER FOR OCSSD EVICTIONS
4.0 - TROUBLESHOOTING CSSDAGENT OR CSSDMONITOR EVICTIONS
4.1 - COMMON CAUSES OF CSSDAGENT OR CSSDMONITOR EVICTIONS
4.2 - FILES TO REVIEW AND GATHER FOR CSSDAGENT OR CSSDMONITOR EVICTIONS
References

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Applies to:

Oracle Server - Enterprise Edition - Version: 11.2.0.1 to 11.2.0.2 - Release: 11.2 to 11.2
Information in this document applies to any platform.

Purpose

This document is to provide a reference for troubleshooting 11.2 Clusterware node evictions. For clusterware node evictions prior to 11.2, see Note: 265769.1

Scope and Application

This document is intended for DBA's and support analysts experiencing clusterware node evictions (reboots).

Troubleshooting 11.2 Clusterware Node Evictions (Reboots)

NODE EVICTION OVERVIEW

The Oracle Clusterware is designed to perform a node eviction by removing one or more nodes from the cluster if some critical problem is detected. A critical problem could be a node not responding via a network heartbeat, a node not responding via a disk heartbeat, a hung or severely degraded machine, or a hung ocssd.bin process. The purpose of this node eviction is to maintain the overall health of the cluster by removing bad members.

1.0 - PROCESS ROLES FOR REBOOTS

OCSSD (aka CSS daemon) - This process is spawned by the cssdagent process. It runs in both
vendor clusterware and non-vendor clusterware environments. OCSSD's primary job is internode health monitoring and RDBMS instance endpoint discovery. The health monitoring includes a network heartbeat and a disk heartbeat (to the voting files). OCSSD can also evict a node after escalation of a member kill from a client (such as a database LMON process). This is a multi-threaded process that runs at an elevated priority and runs as the Oracle user.

Startup sequence: INIT --> init.ohasd --> ohasd --> ohasd.bin --> cssdagent --> ocssd --> ocssd.bin

CSSDAGENT - This process is spawned by OHASD and is responsible for spawning the OCSSD process, monitoring for node hangs (via oprocd functionality), and monitoring to the OCSSD process for hangs (via oclsomon functionality), and monitoring vendor clusterware (via vmon functionality). This is a multi-threaded process that runs at an elevated priority and runs as the root user.

Startup sequence: INIT --> init.ohasd --> ohasd --> ohasd.bin --> cssdagent

CSSDMONITOR - This proccess also monitors for node hangs (via oprocd functionality), monitors the OCSSD process for hangs (via oclsomon functionality), and monitors vendor clusterware (via vmon functionality). This is a multi-threaded process that runs at an elevated priority and runs as the root user.

Startup sequence: INIT --> init.ohasd --> ohasd --> ohasd.bin --> cssdmonitor

2.0 - DETERMINING WHICH PROCESS IS RESPONSIBLE FOR A REBOOT

Important files to review:

• Clusterware alert log in <GRID_HOME>/log/<nodename>
• The cssdagent log(s) in <GRID_HOME>/log/<nodename>/agent/ohasd/oracssdagent_root
• The cssdmonitor log(s) in <GRID_HOME>/log/<nodename>/agent/ohasd/oracssdmonitor_root
• The ocssd log(s) in <GRID_HOME>/log/<nodename>/cssd
• The lastgasp log(s) in /etc/oracle/lastgasp or /var/opt/oracle/lastgasp
• IPD/OS or OS Watcher data
• 'opatch lsinventory -detail' output for the GRID home
• *Messages files:

* Messages file locations:

• Linux: /var/log/messages
• Sun: /var/adm/messages
• HP-UX: /var/adm/syslog/syslog.log
• IBM: /bin/errpt -a > messages.out

Note that the diagcollection.pl script in <GRID_HOME>/bin can be used to obtain the <GRID_HOME>/log files.

11.2 Clusterware evictions should, in most cases, have some kind of meaningful error in the clusterware alert log. This can be used to determine which process is responsible for the reboot. Example message from a clusterware alert log:

[ohasd(11243)]CRS-8011:reboot advisory message from host: sta00129, component: cssagent, with timestamp: L-2009-05-05-10:03:25.340
[ohasd(11243)]CRS-8013:reboot advisory message text: Rebooting after limit 28500 exceeded; disk timeout 27630, network timeout 28500, last heartbeat from CSSD at epoch seconds 1241543005.340, 4294967295 milliseconds ago based on invariant clock value of 93235653

This particular eviction happened when the cssagent timed out heartbeating to the CSSD process (oclsomon functionality). Once you know the process (in the first message), the corresponding logs can be reviewed.

More examples to come later...

If no message is in the evicted node's clusterware alert log, check the lastgasp logs on the local node and/or the clusterware alert logs of other nodes.

3.0 - TROUBLESHOOTING OCSSD EVICTIONS

If you have encountered an OCSSD eviction review common causes in section 3.1 below. If the problem cannot be determined by reviewing the common causes, review and collect the data from section 3.3.

3.1 - COMMON CAUSES OF OCSSD EVICTIONS

• Network failure or latency between nodes. It would take 30 consecutive missed checkins (by default - determined by the CSS misscount) to cause a node eviction.
• Problems writing to or reading from the CSS voting disk. If the node cannot perform a disk heartbeat to the majority of its voting files, then the node will be evicted.
• A member kill escalation. For example, database LMON process may request CSS to remove an instance from the cluster via the instance eviction mechanism. If this times out it could escalate to a node kill.
• An unexpected failure of the OCSSD process, this can be caused by any of the above issues or something else.
• An Oracle bug.

3.2 - FILES TO REVIEW AND GATHER FOR OCSSD EVICTIONS

All files from section 2.0 from all cluster nodes. More data may be required.

4.0 - TROUBLESHOOTING CSSDAGENT OR CSSDMONITOR EVICTIONS

If you have encountered a CSSDAGENT or CSSDMONITOR eviction review common causes in section 4.1 below. If the problem cannot be determined by reviewing the common causes, review and collect the data from section 4.3.

4.1 - COMMON CAUSES OF CSSDAGENT OR CSSDMONITOR EVICTIONS

• An OS scheduler problem. For example, if the OS is getting locked up in a driver or hardware or there is excessive amounts of load on the machine, thus preventing the scheduler from behaving reasonably.
• A thread(s) within the CSS daemon hung.
• An Oracle bug.

4.2 - FILES TO REVIEW AND GATHER FOR CSSDAGENT OR CSSDMONITOR EVICTIONS

All files from section 2.0 from all cluster nodes. More data may be required.

References

NOTE:265769.1 - Troubleshooting 10g and 11.1 Clusterware Reboots
NOTE:301137.1 - OS Watcher User Guide
NOTE:736752.1 - Introducing Cluster Health Monitor (IPD/OS)

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