Add Swap Space on Linux

Find current swap space on the system

# free -m
           total   used    free   shared   buffers  cached
Mem:       16051   15570    481      0       707     12644
-/+ buffers/cache: 2218    13833
Swap:      8189     0      8189

Or

# swapon -s
Filename         Type        Size    Used    Priority
/dev/sda2      partition   8385920    88       -1

 Or

# cat /proc/swaps
Filename         Type        Size    Used    Priority
/dev/sda2      partition   8385920    88       -1

Method 1 - Use Hard Drive Partition

If you have additional hard disk or space available in existing disk then create partition using fdisk command. Assume /dev/sdc1 is newly created partition 

Setup newly created partition as swap area

# mkswap /dev/sdc1

Enable swap partition

# swapon /dev/sdc1

Add following line to /etc/fstab to available even after reboot

# cat /etc/fstab
/dev/sdc1        swap         swap    defaults        0 0

Verify whether newly created swap space is available

# swapon -s
Filename         Type       Size     Used    Priority
/dev/sda2      partition   8385920    88       -1
/dev/sdc1      partition  10234430     0       -2

Method 2 - Use a file for Additional swap space

If you does not have any additional disk then you can create a file on your system and use that for swap space

Create the swap file called 'myswap' using following command (file size in bytes=bs*count)

# dd if=/dev/zero of=/root/myswap bs=1M count=2048

Change the permission of newly created file

# chmod 755 /root/myswap

Make this file as a swap file

# mkswap /root/myswap

Add following line to /etc/fstab to available even after reboot

# cat /etc/fstab
/root/myswap        swap         swap    defaults        0 0

Verify whether newly created swap space is available

# swapon -s
Filename         Type       Size     Used    Priority
/dev/sda2      partition   8385920    88       -1
/root/myswap     file      2097152     0       -2

Deploy 12c Management Agent

Here explain how to add target hosts to enterprise manager

Login to Enterprise Manager via Sysman login
Go to Setup->Add Target->Add Targets Manually

 Select Add Host Targets and Click Add Host Button

Click on Add Button and Add the target host name which need to deploy agent and Click on Next Button

Provide Installation Base Directory and Instance directory on target host

Review the Host Information and click on Deploy Agent button to begin the installation

Now Management Agent will deploy on target host

Ignore the Privileges warning and click on Continue->Continue, All Host

Run the root.sh to complete the Agent deployment

Go to Setup->Add Target->Add Targets Manually and select 'Add Target Declaratively by Specifying Target Monitoring Properties'
Select 'Database Instance' to Target Type and specific hostname for Monitoring Agent and click on 'Add Manually' Button

Provide Database Details of Agent and Test the connection

Agent configuration completed and now can monitor newly added DB through EM

Install 12c Enterprise Manager

Prerequisites 

Download and Install Oracle Database 11g R2 on linux platform

Download Enterprise Manager Cloud control from following link

http://www.oracle.com/technetwork/oem/grid-control/downloads/index.html

If you have performed a default database installation you will need to de-configure Enterprise Manager Database Control. Run the following command as the "oracle" user.

$ emca -deconfig dbcontrol db -repos drop -SYS_PWD <sys pasword> -SYSMAN_PWD <sysman password>

Make following initialization parameter changes and restart the instance

$sqlplus / AS SYSDBA
SQL>ALTER SYSTEM SET processes=300 SCOPE=SPFILE;
SQL>ALTER SYSTEM SET session_cached_cursors=200 SCOPE=SPFILE
SQL>ALTER SYSTEM SET sga_target=2G SCOPE=SPFILE;
SQL>ALTER SYSTEM SET shared_pool_size=600M SCOPE=SPFILE;
SQL>ALTER SYSTEM SET pga_aggregate_target=1G SCOPE=SPFILE;
SQL>ALTER SYSTEM SET job_queue_processes=20 SCOPE=SPFILE;

SQL>SHUTDOWN IMMEDIATE
SQL>STARTUP

If you have done a default installation as described here, the UNDO tablespace will be autoextensible. If you have done a custom installation make sure the UNDO tablespace is at least 200M in size. Also, make sure you have 3 redo logs of at least 300M to prevent a warning during the installation.

Cloud Control Installation

Create Following installation directories for management server and agent

$ mkdir -p /u01/app/oracle/oms12cr3
$ mkdir -p /u01/app/oracle/agent12cr3

Unzip the cloud control media and begin the installation by running runinstaller

$ mkdir em
$ unzip -d em em12103p1_linux64_disk1.zip
$ unzip -d em em12103p1_linux64_disk2.zip
$ unzip -d em em12103p1_linux64_disk3.zip
$ cd em

$ ./runInstaller

If you wish to receive support information enter the e-mail address else skip

If you wish to check for updates enter the details else skip

If you have completed all the prerequisites then installation pass all the checks

Select 'Create a new Enterprise Manager System' and 'simple' option

Enter Middleware and Agent installation locations

Enter Administrator password and Database Details

If you have any additional warnings, check they don't look like show-stoppers, then click the 'OK' button to continue and click 'Install' button to begin the installation

When prompted, run the root scripts, then click the 'OK' button
Make note of the URL below and close. Copy of following information are stored in /u01/app/oracle/oms12cr3/oms/install/setupinfo.txt file.

Login to the EM using above URL.

Startup and Shutdown Enterprise Manager

Oracle Management Server

export OMS_HOME=/u01/app/oracle/oms12cr3/oms
$OMS_HOME/bin/emctl start oms
$OMS_HOME/bin/emctl stop oms
$OMS_HOME/bin/emctl status oms

Agent

export AGENT_HOME=/u01/app/oracle/agent12cr3/core/12.1.0.3.0
$AGENT_HOME/bin/emctl start agent
$AGENT_HOME/bin/emctl stop agent
$AGENT_HOME/bin/emctl status agent