DB2 SQL6048N A communication error occurred during START or STOP DATABASE MANAGER processing Problem solution record

Solve it in the following way

Citing official documentation

How to solve db2start error SQL6048N

Technote (troubleshooting)

Problem(Abstract)

SQL6048N A communication error occurred during START or STOP DATABASE MANAGER processing.

Symptom

When trying to start an instance using the db2start command, the following error is received.

SQL6048N A communication error occurred during START or STOP DATABASE MANAGER processing.

Cause

The examples are shown below :

1. Your system might have a different hostname than the hostname listed in 2.Your system might have a problem with rsh daemon.<INSTANCE_HOME>/sqllib/db2nodes.cfg

Environment

DB2® V9.1, V9.5 and V9.7 on Linux™ or UNIX™ environments

Diagnosing the problem

1. Execute the hostname command and compare the output with the hostname listed in INSTANCE_HOME>/sqllib/db2nodes.cfg<

2. Login as a instance user and run the following command. Run the the following command to display related information:
$ db2_all "echo OK" rshd: 0826-813 Permission is denied. rshd: 0826-813 Permission is denied.

db2 ? SQL6048N

Resolving the problem

Resolve the problem using one of these solutions:

If the hostname displayed by the hostname command is different than the hostname from <INSTANCE_HOME>/sqllib/db2nodes.cfg, then you must modify the db2nodes.cfg record to match the hostname of the system.
If the hostname of the system is a Fully Qualified Domain Name (FQDN) then you must use the FQDN in db2nodes.cfg.

3. Step 1 : Login as instance owner and change the permission of the .rhosts file as follows.

chmod 400 .rhosts

Step 2 : Run the following command to confirm if the rsh daemon is set properly or not. Step 3: Run the or command. This is one of the method to solve the MPP start problem. If user runs the command, SQL6048N will display related information.

$ db2_all "echo OK"

OK
coralpib135: echo OK completed ok

OK
coralpib137: echo OK completed ok

db2stop db2start

$ db2stop
11/29/2011 01:45:13 0 0 SQL1064N DB2STOP processing was successful.
11/29/2011 01:45:13 1 0 SQL1064N DB2STOP processing was successful.
SQL1064N DB2STOP processing was successful.

db2 ?

DB2 SQL6048N Communication error during START or STOP DATABASE MANAGER processing