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This article will explain in detail the differences and connections about has, ohasd, crs and cluster. The content of the article is of high quality, so the editor will share it for you as a reference. I hope you will have a certain understanding of the relevant knowledge after reading this article.

Has is a highly available service, which can be used in restart environment, either stand-alone environment or RAC environment. No matter stand-alone environment or RAC environment, crsctl check has can be executed. In RAC environment, it can be simply understood as a part of cluster.

Ohasd is the concept of has background process

Crs is a cluster-ready service, which is used in RAC environment. If crsctl check crs,crsctl start CRS cannot be executed in a stand-alone environment, not only CRSD will be started, but OHASD, CRSD and CSSD will be started.

Cluster means cluster. When used in RAC environment, crsctl check cluster cannot be executed in a stand-alone environment.

Crsctl check crs and crsctl check cluster cannot be executed in a stand-alone environment, but crsctl stat res, crsctl check css, crsctl check has can be executed

Oracle high availability services (HAS)

Oracle Restart uses Oracle high availability services to start and stop automatically the components managed by Oracle Restart. For example, Oracle high availability services daemons automatically start databases, listeners, and Oracle ASM instances. When Oracle high availability services are disabled, none of the components managed by Oracle Restart are started when a node is rebooted.

Oracle Restart uses the Oracle high availability service to automatically start and stop components managed by Oracle Restart. For example, the Oracle high availability service daemon automatically starts databases, listeners, and Oracle ASM instances. When the Oracle high availability service is disabled, Oracle Restart managed components are not started when the node is restarted.

Crsctl command has

Where command is a verb such as start, stop, or enable. The has object indicates Oracle high availability services

Check Displays the Oracle Restart status.

Config Displays the Oracle Restart configuration.

Disable Disables automatic restart of Oracle Restart.

Enable Enables automatic restart of Oracle Restart.

Start Starts Oracle Restart.

Stop Stops Oracle Restart.

Oracle High Availability Services Daemon (OHASD)

This process anchors the lower part of the Oracle Clusterware stack, which consists of processes that facilitate cluster operations.

Oracle Restart improves the availability of your Oracle database. When you install OracleRestart, various Oracle components can be automatically restarted after ahardware or software failure or whenever your database host computer restarts.

This process fixes the lower part of the Oracle Clusterware stack, which consists of processes that facilitate cluster operations.

OracleRestart can improve the availability of the database. When OracleRestart is installed, after the system has hardware or software problems, or the host restarts, the components managed by OracleRestart can be started automatically.

OHASD is a background daemon that can be used to start and monitor OracleRestart processes. The process is initialized by the / etc/init.d/ohasd script and started by the root user executing ohasd.bin, as follows

[root@pdba ~] # ps-ef | grep has | grep-v grep

Root 5281 1 0 Jun25? 14:28:09 / u01/app/11.2.0/grid/bin/ohasd.bin reboot

Root 13261 1 0 Jun25? 00:00:00 / bin/sh / etc/init.d/init.ohasd run

OHASD cannot kill. Once kill, it will be pulled up again (refer to the meaning of respawn in / etc/initab).

[root@TEST ~] # cat / etc/inittab | grep init.ohasd

H2:35:respawn:/etc/init.d/init.ohasd run > / dev/null 2 > & 1

Note: Oracle Linux 6 (OL6) or Red Hat Linux 6 (RHEL6) has deprecated inittab, rather, init.ohasd will be configured via upstart in / etc/init/oracle-ohasd.conf, however, the process "" / etc/init.d/init.ohasd run "should still be up. Oracle Linux 7 (and Red Hat Linux 7) uses systemd to manage start/stop services (example: / etc/systemd/system/oracle-ohasd.service)

Note: Oracle Linux 6 (OL6) or Red Hat Linux 6 (RHEL6) has deprecated inittab. Instead, init.ohasd will be configured through upstart in / etc/init/oracle-ohasd.conf, but the process "/ etc/init.d/init.ohasd run" should still be started, and Oracle Linux 7 (and Red Hat Linux 7) use systemd to manage starting / stopping services (for example: / etc/systemd/system/oracle-ohasd.service)

[root@pdba ~] # cat / etc/issue

CentOS release 6.8 (Final)

Kernel\ r on an\ m

[root@pdba ~] # cat / etc/init/oracle-ohasd.conf

# Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.

#

# Oracle OHASD startup

Start on runlevel [35]

Stop on runlevel [! 35]

Respawn

Exec / etc/init.d/init.ohasd run > / dev/null 2 > & 1

For standalone server, OHASD is used to manage Oracle Restart and does not require the support of the CRSD process. The following components can be managed using OHASD:

1.CSSD: This is used for Group Services as it was inprevious releases (when it was installed using "localconfig add")

2.ASM Instance: if Automatic Storage Management is used.

3.ASM Disk Groups: if Automatic Storage Management is used.

4.Listeners

5.Database Instances

6.Database Services

7.ONS/EONS: Used for automatic failover of connections usingFast Application Notification (FAN) in a Data Guard environment

Cluster Ready Services (CRS)

Cluster Ready Services Daemon (CRSD)

The primary Oracle Clusterware process that performs high availability recovery and management operations, such as maintaining OCR. Also manages application resources and runs as root user (or by a user in the admin group on Mac OS X-based systems) and restarts automatically upon failure.

The primary Oracle Clusterware process that performs high availability recovery and administrative operations, such as maintaining OCR. It also manages application resources and runs as a root user (or a user in the administrators group on a Mac OS X-based system) and automatically restarts if it fails.

[root@pdb02 ~] # ps-ef | grep crs | grep-v grep

Root 3672 1 0 13:15? 00:00:48 / u01/app/11.2.0/grid/bin/crsd.bin reboot

Cluster

Oracle Clusterware enables servers to communicate with each other, so that they appear to function as a collective unit. This combination of servers is commonly known as a cluster. Although the servers are standalone servers, each server has additional processes that communicate with other servers. In this way the separate servers appear as if they are one system to applications and end users.

Oracle Clusterware enables servers to communicate with each other to make them look like a collective unit. This combination of servers is often referred to as clustering. Although the server is a separate server, each server has other processes that communicate with other servers. In this way, the stand-alone server looks like a system for applications and end users.

CRS

Crsctl start crs

Use the crsctl start crs command to start Oracle High Availability Services on the local server.

Crsctl check crs

Use the crsctl check crs command to check the status of Oracle High Availability Services and the Oracle Clusterware stack on the local server.

Crsctl stop crs

Use the crsctl stop crs command to stop Oracle High Availability Services on the local server.

Cluster

Crsctl start cluster

Use the crsctl start cluster command on any node in the cluster to start the Oracle Clusterware stack.

Crsctl check cluster

Use the crsctl check cluster command on any node in the cluster to check the status of the Oracle Clusterware stack.

Crsctl stop cluster

Use the crsctl stop cluster command on any node in the cluster to stop the Oracle Clusterware stack on all servers in the cluster or specific servers.

Has

Crsctl start has

Use the crsctl start has command to start Oracle High Availability Services on the local server

Crsctl check has

Use the crsctl check has command to check the status of ohasd.

Crsctl stop has

Use the crsctl stop has command to stop Oracle High Availability Services on the local server

The result of execution by a node of RAC

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl config has

CRS-4622: Oracle High Availability Services autostart is enabled.

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl config crs

CRS-4622: Oracle High Availability Services autostart is enabled.

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl config cluster

Parse error:

'cluster' is an invalid argument

[root@node1 grid] # crsctl check crs

CRS-4638: Oracle High Availability Services is online

CRS-4537: Cluster Ready Services is online

CRS-4529: Cluster Synchronization Services is online

CRS-4533: Event Manager is online

-crsctl start CRS not only starts CRSD, but also starts OHASD, CRSD and CSSD.

[root@node1 grid] # crsctl check cluster

CRS-4537: Cluster Ready Services is online

CRS-4529: Cluster Synchronization Services is online

CRS-4533: Event Manager is online

[root@pdba ~] # crsctl check has

CRS-4638: Oracle High Availability Services is online

Crsctl check cssd was replaced by crsctl check css.

[root@node1 ~] # crsctl check cssd

CRS-272: This command remains for backward compatibility only

Cluster Synchronization Services is online

Crsctl check crsd was replaced by crsctl check crs.

[root@node1 grid] # crsctl check crsd

CRS-272: This command remains for backward compatibility only

Cluster Ready Services is online

But there are no commands like crsctl start cssd or crsctl start crsd.

The result of execution by a node of RAC

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl start has

CRS-4123: Oracle High Availability Services has been started.

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl start has

CRS-4640: Oracle High Availability Services is already active

CRS-4000: Command Start failed, or completed with errors.

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl check has

CRS-4638: Oracle High Availability Services is online

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl stop has

CRS-2791: Starting shutdown of Oracle High Availability Services-managed resources on 'pdb02'

CRS-2673: Attempting to stop 'ora.crsd' on' pdb02'

CRS-2677: Stop of 'ora.crsd' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.mdnsd' on' pdb02'

CRS-2673: Attempting to stop 'ora.ctssd' on' pdb02'

CRS-2673: Attempting to stop 'ora.evmd' on' pdb02'

CRS-2673: Attempting to stop 'ora.asm' on' pdb02'

CRS-2677: Stop of 'ora.ctssd' on' pdb02' succeeded

CRS-2677: Stop of 'ora.evmd' on' pdb02' succeeded

CRS-2677: Stop of 'ora.mdnsd' on' pdb02' succeeded

CRS-2677: Stop of 'ora.asm' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.cluster_interconnect.haip' on' pdb02'

CRS-2677: Stop of 'ora.cluster_interconnect.haip' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.cssd' on' pdb02'

CRS-2677: Stop of 'ora.cssd' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.crf' on' pdb02'

CRS-2677: Stop of 'ora.crf' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.gipcd' on' pdb02'

CRS-2677: Stop of 'ora.gipcd' on' pdb02' succeeded

CRS-2673: Attempting to stop 'ora.gpnpd' on' pdb02'

CRS-2677: Stop of 'ora.gpnpd' on' pdb02' succeeded

CRS-2793: Shutdown of Oracle High Availability Services-managed resources on 'pdb02' has completed

CRS-4133: Oracle High Availability Services has been stopped

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl check has

CRS-4639: Could not contact Oracle High Availability Services

[root@pdb02 ~] # / u01/app/11.2.0/grid/bin/crsctl stop has

CRS-2796: The command may not proceed when Cluster Ready Services is not running

CRS-4687: Shutdown command has completed with errors.

CRS-4000: Command Stop failed, or completed with errors.

Result of stand-alone execution

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl start has

CRS-4123: Oracle High Availability Services has been started.

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl start has

CRS-4640: Oracle High Availability Services is already active

CRS-4000: Command Start failed, or completed with errors.

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl check has

CRS-4638: Oracle High Availability Services is online

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl stop has

CRS-2791: Starting shutdown of Oracle High Availability Services-managed resources on 'giosonly'

CRS-2673: Attempting to stop 'ora.LISTENER.lsnr' on' giosonly'

CRS-2673: Attempting to stop 'ora.DATA.dg' on' giosonly'

CRS-2677: Stop of 'ora.LISTENER.lsnr' on' giosonly' succeeded

CRS-5022: Stop of resource "ora.DATA.dg" failed: current state is "UNKNOWN"

CRS-2675: Stop of 'ora.DATA.dg' on' giosonly' failed

CRS-2679: Attempting to clean 'ora.DATA.dg' on' giosonly'

CRS-2681: Clean of 'ora.DATA.dg' on' giosonly' succeeded

CRS-2673: Attempting to stop 'ora.asm' on' giosonly'

CRS-2677: Stop of 'ora.asm' on' giosonly' succeeded

CRS-2673: Attempting to stop 'ora.cssd' on' giosonly'

CRS-2677: Stop of 'ora.cssd' on' giosonly' succeeded

CRS-2673: Attempting to stop 'ora.evmd' on' giosonly'

CRS-2677: Stop of 'ora.evmd' on' giosonly' succeeded

CRS-2793: Shutdown of Oracle High Availability Services-managed resources on 'giosonly' has completed

CRS-4133: Oracle High Availability Services has been stopped.

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl check has

CRS-4639: Could not contact Oracle High Availability Services

[root@GIOSONLY app] # / u01/app/oracle/product/11.2.0/grid/bin/crsctl stop has

CRS-4544: Unable to connect to OHAS

CRS-4000: Command Stop failed, or completed with errors.

About has, ohasd, crs, cluster differences and connections are shared here, I hope the above content can be of some help to you, can learn more knowledge. If you think the article is good, you can share it for more people to see.

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