Know about RAC Clusterware Process OPROCD

OPROCD introduced in 10.2.0.4 Linux and other Unix platform.

• Fencing
  • Cluster handling of nodes that should not have access to shared resources
  • STONITH – Power cycle the node
  • PCW – nodes fence themselves through the reboot(8) command
  • Fabric Fencing from Polyserve
    • Healthy nodes send SNMP msgs to Fabric switch to disable SAN access from unhealthy nodes [ fence them out ]
    • Server is left in up state to view logs etc.

• Oracle’s Cluster I/O Fencing solution
• Only started on Unix platforms when vendor Clusterware is not running
• Does not run on Windows and Linux!
• Takes 2 parameters
  • Timeout value [ length of time between executions ]
  • Margin [ leeway for dispatches ]
  • Oproc.debug –t 1000 –m 500
• In fatal mode node will get reboot’ed
• In non-fatal mode error messages will be logged

OPROCD – This process is spawned in any non-vendor clusterware environment, except
on Windows where Oracle uses a kernel driver to perform the same actions and Linux
prior to version 10.2.0.4. If oprocd detects problems, it will kill a node via C
code. It is spawned in init.cssd and runs as root. This daemon is used to detect
hardware and driver freezes on the machine. If a machine were frozen for long enough
that the other nodes evicted it from the cluster, it needs to kill itself to prevent
any IO from getting reissued to the disk after the rest of the cluster has remastered
locks.”

*** Oprocd log locations:
In /etc/oracle/oprocd or /var/opt/oracle/oprocd depending on version/platform.

The OPROCD executable sets a signal handler for the SIGALRM handler and sets the interval timer based on the to-millisec parameter provided. The alarm handler gets the current time and checks it against the time that the alarm handler was last entered. If the difference exceeds (to-millisec + margin-millisec), it will fail; the production version will cause a node reboot.

In fatal mode, OPROCD will reboot the node if it detects excessive wait. In Non Fatal mode, it will write an error message out to the file .oprocd.log in one of the following directories.

Oracle clusterware has the following three daemons which may be responsible for panicing the node. It is possible that some other external entity may have rebooted the node. In the context of this discussion, we will assume that the reboot/panic was done by an Oracle clusterware daemon.

* Oprocd – Cluster fencing module
* Cssd – Cluster sychronization module which manages node membership
* Oclsomon – Cssd monitor which will monitor for cssd hangs

OPROCD This is a daemon that only gets activated when there is no vendor clusterware present on the OS.This daemon is also not activated to run on Windows/Linux. This daemon runs a tight loop and if it is not scheduled for 1.5 seconds, will reboot the node.
CSSD This daemon pings the other members of the cluster over the private network and Voting disk. If this does not get a response for Misscount seconds and Disktimeout seconds respectively, it will reboot the node.
Oclsomon This daemon monitors the CSSD to ensure that CSSD is scheduled by the OS, if it detects any problems it will reboot the node.

A sample log looks like
May 11 18:13:15.528 | INF | monitoring started with timeout(1000), margin(500)
May 11 18:13:15.548 | INF | normal startup, setting process to fatal mode
May 12 11:43:00.899 | INF | shutting down from client request
May 12 11:43:00.899 | INF | exiting current process in NORMAL mode
May 12 12:10:43.984 | INF | monitoring started with timeout(1000), margin(500)
May 13 11:29:37.528 | INF | shutting down from client request
May 13 11:29:37.528 | INF | exiting current process in NORMAL mode

When fatal mode is disabled, OPROCD will write the following to the log file and exit:
May 10 18:01:40.668 | INF | monitoring started with timeout(1000), margin(500)
May 10 18:23:02.490 | ERR | AlarmHandler:? timeout(1739751316) exceeds interval(1000000000)+margin(500000000)

[root@rh2 ~]# ps -ef|grep oprocd|grep -v grep
root     19763     1  0 Jun27 ?        00:00:00 oprocd start

[root@rh2 oprocd]# cd /etc/oracle/oprocd

[root@rh2 oprocd]# ls -l
total 20
drwxrwx--- 2 root oinstall 4096 Jun 27 23:52 check
drwxrwx--- 2 root oinstall 4096 Mar 29 22:37 fatal
-rwxr--r-- 1 root root      512 Jun 27 23:52 rh2.oprocd.lgl
-rw-r--r-- 1 root root      171 Jun 27 23:52 rh2.oprocd.log
drwxrwx--- 2 root oinstall 4096 Jun 27 23:52 stop

[root@rh2 oprocd]# cat rh2.oprocd.log
Jun 27 23:52:47.861 | INF | monitoring started with timeout(1000), margin(500), skewTimeout(125)
Jun 27 23:52:47.864 | INF | normal startup, setting process to fatal mode

[root@rh2 oprocd]# oprocd

usage:  oprocd [start | startInstall | stop | check | enableFatal| help | -?]

        run [ -t | -m | -g | -f  | -e]   foreground startup
              -t           timeout in ms
              -m            timout margin in ms
              -e           clock skew epsilon in ms
              -g         group name to enable fatal
              -f                    fatal startup

        start  [-t | -m  | -e]           starts the daemon
                -t         timeout in ms
                -m          timout margin in ms
                 -e         clock skew epsilon in ms

        startInstall [ -t | -m | -g  | - e] start process in install mode
                       -t    timeout in ms
                       -m     timout margin in ms
                       -e    clock skew epsilon in ms
                       -g  group name to enable fatal

        enableFatal  [ -t ]             force install mode process to fatal
                       -t    timeout for response in ms
        stop         [ -t ]             stops running daemon
                       -t    timeout for response in ms
        check        [ -t ]           checks status of daemon
                       -t    timeout for response in ms
        help                          this help information
        -?                            same as help above

[root@rh2 oprocd]# oprocd stop
Jun 28 00:17:36.604 | INF | daemon shutting down

Oracle ClusterwareProcess Monitor (OPROCD) From Julian Dyke

Process Monitor Daemon
Provides Cluster I/O Fencing

Implemented on Unix systems
Not required with third-party clusterware
Implemented in Linux in 10.2.0.4 and above
In 10.2.0.3 and below hangcheck timer module is used

Provides hangcheck timer functionality to maintain cluster integrity
Behaviour similar to hangcheck timer
Runs as root
Locked in memory
Failure causes reboot of system
See /etc/init.d/init.cssd for operating system reboot commands

OPROCD takes two parameters
-t  - Timeout value
Length of time between executions (milliseconds)
Normally defaults to 1000
-m - Margin
Acceptable margin before rebooting (milliseconds)
Normally defaults to 500

Parameters are specified in /etc/init.d/init.cssd
OPROCD_DEFAULT_TIMEOUT=1000
OPROCD_DEFAULT_MARGIN=500

Contact Oracle Support before changing these values

/etc/init.d/init.cssd can increase OPROCD_DEFAULT_MARGIN based on two CSS variables
reboottime (mandatory)
diagwait (optional)
Values can for these be obtained using

[root@server3]# crsctl get css reboottime
[root@server3]# crsctl get css diagwait

Both values are reported in seconds
The algorithm is

If diagwait > reboottime then
OPROCD_DEFAULT_MARGIN := (diagwait - reboottime) * 1000

Therefore increasing diagwait will reduce frequency of reboots e.g

[root@server3]# crsctl set css diagwait 13