Deployment and Maintenance FAQs

Environment Initialization FAQs

Q1: What parameter values need to be changed in clusterconfig.xml sample configuration file?

The node name and IP address need to be changed.

<?xml version="1.0" encoding="UTF-8"?>
<ROOT>
    <!-- Overall information about MogDB -->
    <CLUSTER>
        <PARAM name="clusterName" value="dbCluster" />
        <PARAM name="nodeNames" value="mogdb-kernel-0002" />
        <PARAM name="backIp1s" value="172.16.0.245"/>
        <PARAM name="gaussdbAppPath" value="/opt/mogdb/app" />
        <PARAM name="gaussdbLogPath" value="/opt/mogdb/mogdb_log/omm" />
        <PARAM name="gaussdbToolPath" value="/opt/mogdb/tool" />
        <PARAM name="corePath" value="/opt/mogdb/corefile"/>
        <PARAM name="clusterType" value="single-inst"/>
    </CLUSTER>

<!-- Information about node deployment on each server -->
    <DEVICELIST>
        <!-- Information about the node deployment on node1 -->
        <DEVICE sn="1000001">
            <PARAM name="name" value="mogdb-kernel-0002"/>
            <PARAM name="azName" value="AZ1"/>
            <PARAM name="azPriority" value="1"/>
            <!-- If only one NIC is available for the server, set backIP1 and sshIP1 to the same IP address. -->
            <PARAM name="backIp1" value="172.16.0.245"/>
            <PARAM name="sshIp1" value="172.16.0.245"/>

            <!--dbnode-->
            <PARAM name="dataNum" value="1"/>
            <PARAM name="dataPortBase" value="26000"/>
            <PARAM name="dataNode1" value="/mogdb/data/db1"/>
        </DEVICE>
    </DEVICELIST>
</ROOT>

Script Initialization FAQs

Q2: What should I do if it is prompted that the parameter value of the configuration file does not match the system environment variable value?

Failed to check the preinstall repeat condition.gaussdbToolPath [/opt/enmo/wisery] is not same with environment [/opt/mogdb/tool]

You can change the value of gaussdbToolPath in clusterconfig.xml to /opt/mogdb/tool.

Note:

This problem occurs mainly because the system has installed MogDB before and the environment may not be fully cleared, so there will be a situation that the parameter value in the configuration file does not match the system environment variable value, which will lead to the failure of execution. You can change the value of the parameter that reports an error in clusterconfig.xml configuration file to the same value as that of the parameter in the environment variable file.

You can run vi ~/.bashrc as user omm to view the environment variables.

Q3: What should I do if it is prompted that I do not have permission to run the command?

Fixing server package owner.
[GAUSS-51400] : Failed to execute the command: su - omm -c 'cd '/opt/software/mogdb/''. Error:
-bash: line 0: cd: /opt/software/mogdb/: Permission denied

Run chmod 755 -R /opt/software to grant permissions to the directory, and then run the script initialization command again.

Q4: What should I do if the symbolic link creation fails?

In:failed to create symbolic link 'usr/bin/python3': File exists

Delete python3 from the usr/bin/ directory and run the In command again.

Q5: What should I do if it is prompted that the host name is not in the cluster?

GAUSS-51619: "The host name [host-172-16-0-195] is not in the cluster."

This is because the actual host name is host-172-16-0-195, not mogdb-kernel-0006, so you need to change the node name in clusterconfig.xml to host-172-16-0-195.

Q6: What should I do if it is prompted the following error?

[GAUSS-50202]:The /opt/mogdb must be empty. Or user [omm] has write permission to directory /opt/mogdb. Because it will create symbolic link [/opt/mogdb/app] to install path [/opt/mogdb/app_e0e9f58d] in gs_install process with this user.

Run vi ~/.bashrc as user omm to clear the environment variables and execute the initialization script again.

Q7: What should I do if an error related to certain dependency software is prompted?

/opt/software/mogdb/bin/mogdb: error while loading shared libraries: libnsl.so.1: cannot open shared object file: No such file or directory
no data was returned by command ""/opt/software/mogdb/bin/mogdb" -V"
The program "mogdb" is needed by gs_initdb but was not found in the
same directory as "/opt/software/mogdb/bin/gs_initdb".
Check your installation.

Reinstall the dependency software libnsl*.

Installation FAQs

Q8: What should I do if it is prompted that the cluster has been installed?

[GAUSS-51400] : Failed to execute the command: source /home/omm/.bashrc;python3 '/opt/mogdb/tool/script/local/CheckInstall.py' -U omm:dbgrp -R /opt/mogdb/app -l /opt/mogdb/mogdb_log/omm/omm/om/gs_local.log -X /opt/software/mogdb/clusterconfig.xml.Error:
Checking old installation.
[GAUSS-51806] : The cluster has been installed.

Run vi ~/.bashrc to view the environment variables, change GAUSS_ENV=2 to GAUSS_ENV=1, and run the install command again.

Q9: What should I do if the following error is prompted?

[GAUSS-51400] : Failed to execute the command: source /home/omm/.bashrc;python3 '/opt/mogdb/tool/script/local/CheckInstall.py' -U omm:dbgrp -R /opt/mogdb/app -l /opt/mogdb/mogdb_log/omm/omm/om/gs_local.log -X /opt/software/mogdb/clusterconfig.xml.Error:
Checking old installation.
Successfully checked old installation.
Checking SHA256.
Successfully checked SHA256.
Checking kernel parameters.
Successfully checked kernel parameters.
Checking directory.
[GAUSS-50202] : The /opt/mogdb/app_b75b585a must be empty.

Switch to /opt/mogdb/app_b75b585a directory as user root, run rm -rf * to delete all files in the directory, and run the install command again.

Q10: What should I do if it is prompted that the socket file already exists?

[GAUSS-50200] : The socket file already exists. Port:26000.

You can change the dataPortBase value in clusterconfig.xml to a port that is available.

Post-Deployment FAQs

Failed to start database via gs_om -t start: Changed the host name via hostnamectl set after standard installation

Applicable to:

MogDB 1.1.0
MogDB 2.0.0
MogDB 2.0.1
MogDB single node

The solution in this document is for the x86 architecture.

Symptom:

After the standard installation is finished (single node), when hostnamectl set is run to change the host name, and gs_om -t start is run to start the database, the start fails.

For example:

Change the host name from mogdb-kernel-0005 to www.mogdb.com by running hostnamectl set as user root.

[root@mogdb-kernel-0005 ~]# hostnamectl
Static hostname: mogdb-kernel-0005
      Icon name: computer-vm
        Chassis: vm
     Machine ID: de03a5f3bf5a4b7e9df939c9dc5b428d
        Boot ID: 828bfbe948ed4de7aff2a059103a0eaa
 Virtualization: kvm
 Operating System: CentOS Linux 7 (Core)
    CPE OS Name: cpe:/o:centos:centos:7
         Kernel: Linux 3.10.0-1160.15.2.el7.x86_64
   Architecture: x86-64
[root@mogdb-kernel-0005 ~]# id
uid=0(root) gid=0(root) groups=0(root)
[root@mogdb-kernel-0005 ~]# hostname
mogdb-kernel-0005
[root@mogdb-kernel-0005 ~]# hostnamectl set-hostname www.mogdb.com

Run the following command as any user to see if the host name is successfully changed.
```
[root@mogdb-kernel-0005 ~]# hostname
www.mogdb.com
```

Run the following command as user omm to stop the database.

[root@mogdb-kernel-0005 ~]# su - omm
Last login: Tue Jul 27 11:18:16 CST 2021 on pts/1
[omm@www ~]$ gs_ctl stop -D /mogdb/data/db1
[2021-07-27 11:19:20.283][32166][][gs_ctl]: gs_ctl stopped ,datadir is /mogdb/data/db1
waiting for server to shut down.... done
server stopped

Run the following command as user omm to start the database.

[omm@www ~]$ gs_om -t start

Starting cluster.
=========================================

=========================================
[GAUSS-53600]: Can not start the database, the cmd is source /home/omm/.bashrc; python3 '/opt/enmo/wisequery/script/local/StartInstance.py' -U omm -R /opt/mogdb/app -t 300 --security-mode=off,  Error:
[GAUSS-51400] : Failed to execute the command: source /home/omm/.bashrc; python3 '/opt/enmo/wisequery/script/local/StartInstance.py' -U omm -R /opt/mogdb/app -t 300 --security-mode=off. Error:
[FAILURE] mogdb-kernel-0005

Purpose:

After the standard installation (single node) is finished , when the host name is changed through modip.py, and gs_om -t start is run to start the command, the database starts successfully.

Resolution:

Create modip.py as user omm.

[omm@www ~]$ cd
[omm@www ~]$ pwd
/home/omm
[omm@www ~]$ vi modip.py

# -*- coding:utf-8 -*-

import sys
##sys.path.append(r'$GPHOME/script/')
sys.path.append(r'/opt/enmo/wisequery/script/')
from gspylib.common.DbClusterInfo import dbClusterInfo

oldIP = '172.16.0.176'
newIP = '172.16.0.176'
oldnodename = 'mogdb-kernel-0005'
newnodename = 'www.mogdb.com'
##Output file directory
tmpDir = r'/home/omm'
dbuser = 'omm'

c1=dbClusterInfo()
c1.initFromStaticConfig(dbuser)

for node in c1.dbNodes:
    if node.backIps[0] == oldIP:
        node.backIps[0] = newIP
    if len(node.virtualIp):
        if node.virtualIp[0] == oldIP:
            node.virtualIp[0] = newIP
    if node.name == oldnodename:
        node.name = newnodename
    if node.sshIps[0] == oldIP:
        node.sshIps[0] = newIP
    for dn in node.datanodes:
        if dn.listenIps[0] == oldIP:
            dn.listenIps[0] = newIP
        if dn.haIps[0] == oldIP:
            dn.haIps[0] = newIP
        for peerdn in dn.peerInstanceInfos:
            if len(peerdn.peerHAIPs):
                if peerdn.peerHAIPs[0] == oldIP:
                    peerdn.peerHAIPs[0] = newIP
for node in c1.dbNodes:
    staticConfigPath_dn = "%s/cluster_static_config_%s" % (tmpDir, node.name)
    c1.saveToStaticConfig(staticConfigPath_dn, node.id)
    print(staticConfigPath_dn)

**Note：**You need to modify the IP address and host name according to the actual situation. In this example, the IP address is 172.16.0.176, the old host name is mogdb-kernel-0005, and the new host name is www.mogdb.com.

Run the following command to generate the static configuration file of the cluster.
```
[omm@www ~]$ python3 modip.py
```
The following output indicates that the command is run successfully.
```
/home/omm/cluster_static_config_www.mogdb.com
```

Run the following command to replace the original file.

[omm@www ~]$ mv /opt/mogdb/app/bin/cluster_static_config /opt/mogdb/app/bin/cluster_static_config_mogdb.com

[omm@www ~]$ cp /home/omm/cluster_static_config_www.mogdb.com /opt/mogdb/app/bin/cluster_static_config

Run the following command to start the database.

[omm@www ~]$ gs_om -t start

Starting cluster.
=========================================

[SUCCESS] www.mogdb.com

2021-07-26 16:20:42.938 60fe7056.1 [unknown] 139667408496384 [unknown] 0 dn_6001 01000  0 [BACKEND] WARNING: could not create any HA TCP/IP sockets
=========================================

Successfully started.