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Archive for August, 2018

Postgresql Error – could not connect to server, Is the server accepting connections on Unix domain socket “/tmp/.s.PGSQL.5432”?

Posted by FatDBA on August 31, 2018

Hey Mates,

I have got this new test box for some POCs related with Data Migration between Oracle and PostgreSQL, and this is the very first time i tried to connect with psql on this server and got an error. This was a newly provisioned server with Postgresql 8.4 installed.

Error is something related with the connection settings and is pasted below.

[root@fatdba ~]# psql

psql: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/tmp/.s.PGSQL.5432"?

I tried to initialize the server and started the services on the machine and it was started smoothly with no error.

[root@fatdba ~]# service postgresql initdb
Initializing database:
                                                           [  OK  ]
[root@fatdba ~]# service postgresql start
Starting postgresql service:

I tried to connect with the database once again and this time got a different set of error which is now related with Authentication which was Ident based. But this gave me an idea that something is related with the authentication protocol what’s bothering the database to start and to verify that I’ve checked pg_hba configuration file and changed the method to ‘Trust’ for this host connection type and did a restart of postgres serviced. And that worked!

[root@fatdba data]# psql -U postgres -W
Password for user postgres:
psql: FATAL:  Ident authentication failed for user "postgres"

[root@fatdba data]# vi pg_hba.conf
[root@fatdba data]#
# TYPE  DATABASE    USER        CIDR-ADDRESS          METHOD
# IPv4 local connections:
host    all         all         127.0.0.1/32          trust
host    all         all         192.168.145.129/32    trust


[root@fatdba data]# service postgresql restart
Stopping postgresql service:                               [  OK  ]
Starting postgresql service:                               [  OK  ]
[root@fatdba data]#
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12c OEM Error: LongOpManager$ZombieDetection:1017

Posted by FatDBA on August 31, 2018

Hey Pals,

I am sure, few of the us who have the 12c EM configured on their systems must have received one of the annoying alert/incident where the EM Agent on the server has reported
something about the ‘Zombie’ processes repeatedly.

I recently encountered one such issue with this Production system where the 12c agent frequently sending zombie related alerts, like one below. So, this post of all about handling such issues
and how to fix them or to avoid them.

Host=dixitlab.asi.dixson.corp 
Target type=Agent 
Target name=dixitlab.asi.dixson.corp:3873 
Message=Problem: java.lang.Throwable:oracle.sysman.gcagent.tmmain.execution.LongOpManager$ZombieDetection:1017 
Severity=Critical 
Problem creation time=May 5, 2018 10:22:48 AM ADST 
Last updated time=Aug 29, 2018 1:00:47 AM ADST 
Problem ID=113 
Problem key=java.lang.Throwable:oracle.sysman.gcagent.tmmain.execution.LongOpManager$ZombieDetection:1017 
Incident count=5 
Problem Status=New 
Priority=None 
Escalated=No 
Problem acknowledged By Owner=No 
Rule Name=OEM12c-Problems,Enterprise Problems 
Rule Owner=SYSMAN

Next quick thing in such cases is always checking the agent (gcagent) logs to understand the exact error or issues with EM or Agent.
And as expected the logs has something interesting in them, i saw a DEBUG message captured where Zombie Detection was initiated by the agent after a delay of lot of attempts.
This happens when an EM Agent task such as collecting metrics is running more than the expected time, the process is marked as a zombie and is one of the leading causes of agent crash or halt.

X-AGENT_PERSISTENCE_WAIT_TIME: 60
X-AGENT_PERSISTENCE_ID: https://dixitlab1.asi.dixson.corp:1830/emd/main/
2018-08-29 17:10:26,050 [31:858161EB] DEBUG - Submitting task ZombieDetector for execution
2018-08-29 17:10:26,050 [216:1AE716D8] DEBUG - Begin task ZombieDetector on Thread: GC.SysExecutor.8
2018-08-29 17:10:26,050 [216:69BEAC9D:GC.SysExecutor.8 (ZombieDetector)] DEBUG - Scheduling next ZombieDetector.Task after delay 60000 including periodShift of 0 milliseconds

There are few of the ways to avoid such issues.
1. Set _zombieSuspensions=TRUE
2. Set _canceledThreadWait=900
3. set _zombieThreadPercentThreshold=0

Other way, that is to avoid the alerts/incidents you can set one of the ‘Hidden’ parameter “_zombieCreateIncident=” to FALSE and set it in the agent configuration file followed by agent restart.
This 

[oracle@dixitlab config]$
[oracle@dixitlab config]$ pwd
/u01/app/oracle/new_agent12c/agent_inst/sysman/config


[oracle@dixitlab config]$ more emd.properties|grep _zombieCreateIncident
_zombieCreateIncident=false
[oracle@dixitlab config]$




[oracle@dixitlab bin]$
[oracle@dixitlab bin]$ ./emctl status agent
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
Agent Version          : 12.1.0.5.0
OMS Version            : 12.1.0.5.0
Protocol Version       : 12.1.0.1.0
Agent Home             : /u01/app/oracle/new_agent12c/agent_inst
Agent Log Directory    : /u01/app/oracle/new_agent12c/agent_inst/sysman/log
Agent Binaries         : /u01/app/oracle/new_agent12c/core/12.1.0.5.0
Agent Process ID       : 2978
Parent Process ID      : 12860
Agent URL              : https://dixitlab.asi.dixson.corp:3873/emd/main/
Local Agent URL in NAT : https://dixitlab.asi.dixson.corp:3873/emd/main/
Repository URL         : https://dixitlab1.asi.dixson.corp:4900/empbs/upload
Started at             : 2018-08-29 01:01:08
Started by user        : oracle
Operating System       : Linux version 2.6.32-696.20.1.el6.x86_64 (amd64)
Last Reload            : (none)
Last successful upload                       : 2018-08-29 17:28:20
Last attempted upload                        : 2018-08-29 17:28:20
Total Megabytes of XML files uploaded so far : 1.03
Number of XML files pending upload           : 0
Size of XML files pending upload(MB)         : 0
Available disk space on upload filesystem    : 52.74%
Collection Status                            : Collections enabled
Heartbeat Status                             : Ok
Last attempted heartbeat to OMS              : 2018-08-29 17:29:16
Last successful heartbeat to OMS             : 2018-08-29 17:29:16
Next scheduled heartbeat to OMS              : 2018-08-29 17:30:16

---------------------------------------------------------------



[oracle@dixitlab bin]$ ./emctl stop agent
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
Stopping agent ...
 stopped.
[oracle@dixitlab bin]$
[oracle@dixitlab bin]$ ./emctl status agent
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
Agent is Not Running
[oracle@dixitlab bin]$
[oracle@dixitlab bin]$
[oracle@dixitlab bin]$ ./emctl start agent
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
Starting agent .............................. started.
[oracle@dixitlab bin]$
[oracle@dixitlab bin]$
[oracle@dixitlab bin]$ ./emctl status agent
Oracle Enterprise Manager Cloud Control 12c Release 5
Copyright (c) 1996, 2015 Oracle Corporation.  All rights reserved.
---------------------------------------------------------------
Agent Version          : 12.1.0.5.0
OMS Version            : 12.1.0.5.0
Protocol Version       : 12.1.0.1.0
Agent Home             : /u01/app/oracle/new_agent12c/agent_inst
Agent Log Directory    : /u01/app/oracle/new_agent12c/agent_inst/sysman/log
Agent Binaries         : /u01/app/oracle/new_agent12c/core/12.1.0.5.0
Agent Process ID       : 2664
Parent Process ID      : 2455
Agent URL              : https://dixitlab.asi.dixson.corp:3873/emd/main/
Local Agent URL in NAT : https://dixitlab.asi.dixson.corp:3873/emd/main/
Repository URL         : https://dixitlab1.asi.dixson.corp:4900/empbs/upload
Started at             : 2018-08-29 17:33:05
Started by user        : oracle
Operating System       : Linux version 2.6.32-696.20.1.el6.x86_64 (amd64)
Last Reload            : (none)
Last successful upload                       : 2018-08-29 17:34:34
Last attempted upload                        : 2018-08-29 17:34:34
Total Megabytes of XML files uploaded so far : 0.03
Number of XML files pending upload           : 0
Size of XML files pending upload(MB)         : 0
Available disk space on upload filesystem    : 52.71%
Collection Status                            : Collections enabled
Heartbeat Status                             : Ok
Last attempted heartbeat to OMS              : 2018-08-29 17:34:24
Last successful heartbeat to OMS             : 2018-08-29 17:34:24
Next scheduled heartbeat to OMS              : 2018-08-29 17:35:24

---------------------------------------------------------------
Agent is Running and Ready
[oracle@dixitlab bin]$


Hope It Helps
Prashant Dixit

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