How to pause an Oracle database

Sometimes it is useful to pause a database, and let it finish the running jobs at a later time.
Particularly in environments with shared resources contention may occur. Important databases need to be prioritized while less important ones should be suspended.

For this purpose, you can use the "suspend" command:

alter system suspend;

Alert log:

Mon Oct 05 10:14:49 2015
Suspending database after alter system suspend command

The database_status field in v$instance will reflect the new state of the database:

SQL> select database_status from v$instance;

 DATABASE_STATUS
-----------------

SUSPENDED

When you are ready to resume database activity, issue the following command:

alter system resume;

More info: Oracle Documentation

How to recursively zip a folder and its subfolders

Use the -r flag to indicate recursive zipping:

zip -r myfile.zip myfolder

How to unzip multiple files on a Unix-based operating systems

When extracting multiple zip files, remember to use single quotes to mask the zip-files:

unzip '*.zip'

For example, when unpacking the files needed to install Oracle 11.2.0.4:

[oracle@lx01 Downloads]$ ls -latr
total 5586768
-rwxr-x---.  1 root   root     1395582860 Sep  2 10:14 p13390677_112040_Linux-x86-64_1of7.zip
-rwxr-x---.  1 root   root     1151304589 Sep  2 10:14 p13390677_112040_Linux-x86-64_2of7.zip
-rwxr-x---.  1 root   root     1205251894 Sep  2 10:15 p13390677_112040_Linux-x86-64_3of7.zip
-rwxr-x---.  1 root   root      656026876 Sep  2 10:16 p13390677_112040_Linux-x86-64_4of7.zip
-rwxr-x---.  1 root   root      599170344 Sep  2 10:16 p13390677_112040_Linux-x86-64_5of7.zip
-rwxr-x---.  1 root   root      488372844 Sep  2 10:16 p13390677_112040_Linux-x86-64_6of7.zip
-rwxr-x---.  1 root   root      119521122 Sep  2 10:16 p13390677_112040_Linux-x86-64_7of7.zip
drwx------. 17 oracle oinstall       4096 Sep  2 10:27 ..
drwxr-xr-x.  2 oracle oinstall       4096 Sep  2 10:34 .
[oracle@lx01 Downloads]$ unzip 'p13390677_112040_Linux-x86-64_*.zip'

Without the quotes, unzip will look for "zip files within zip files".

Thanks to Chris Jean for the tip!

Oracle 11g out-of-place vs. in-place database upgrades

Starting with Oracle 11gR2, Oracle changed their patching strategy.

Previously, a patch set was supposed to be downloaded and installed into an existing ORACLE_HOME.
After 11.2, a "patch set" is really a full release, bundled in a number of zip files.

The default patching method is the "out-out-place", which means that every time customers need to upgrade to a new patch set (say, 11.2.0.4), a new ORACLE_HOME should be created, and the new binaries should be installed here.

So you will potentially end up with a number of ORACLE_HOME on your server, and you can choose to run your database out of either of these, upgrading whenever you please.

See Mike Dietrich's post about the same topic for more details.

How to fix error thrown by OPatch: java.lang.NullPointerException

Problem:

Opatch throws the following error when you are querying the inventory:

[oracle@lx01 ~]$ opatch lsinventory
Oracle Interim Patch Installer version 11.2.0.3.11
Copyright (c) 2015, Oracle Corporation.  All rights reserved.


Oracle Home       : /u01/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/oraInventory
   from           : /u01/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version    : 11.2.0.3.11
OUI version       : 11.2.0.1.0
Log file location : /u01/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-09-02_08-52-28AM_1.log

Lsinventory Output file location : /u01/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/lsinv/lsinventory2015-09-02_08-52-28AM.txt

--------------------------------------------------------------------------------
java.lang.NullPointerException
 at oracle.sysman.oii.oiin.OiinNetOps.addNICInfo(OiinNetOps.java:144)
 at oracle.sysman.oii.oiin.OiinNetOps.computeNICList(OiinNetOps.java:109)
 at oracle.sysman.oii.oiin.OiinNetOps.(OiinNetOps.java:76)
 at oracle.sysman.oii.oiin.OiinNetOps.getNetOps(OiinNetOps.java:90)
 at oracle.sysman.oii.oiix.OiixNetOps.getFullHostName(OiixNetOps.java:49)
 at oracle.opatch.LsInventoryPrinter.printLocalMachineInfo(LsInventoryPrinter.java:2336)
 at oracle.opatch.LsInventorySession.loadAndPrintInventory(LsInventorySession.java:480)
 at oracle.opatch.LsInventorySession.process(LsInventorySession.java:317)
 at oracle.opatch.OPatchSession.main(OPatchSession.java:2120)
 at oracle.opatch.OPatch.main(OPatch.java:626)
Local Machine Information::
Hostname: lx01.oric.no
ARU platform id: 226
ARU platform description:: Linux x86-64

Installed Top-level Products (1): 

Oracle Database 11g                                                  11.2.0.1.0
There are 1 products installed in this Oracle Home.


There are no Interim patches installed in this Oracle Home.


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

OPatch succeeded.

Cause:
In my case, the file /etc/hosts was incorrectly configured.

Solution:
Configure the file /etc/hosts correctly.

[root@lx01 ~]# ifconfig 
enp0s3: flags=4163  mtu 1500
        inet 192.168.0.55  netmask 255.255.255.0  broadcast 192.168.0.255

Check the /etc/hosts:

[root@lx01 ~]# cat /etc/hosts
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
192.168.1.55 lx01.oric.no lx01
[oracle@lx01 ~]$ vi /etc/hosts

Update the incorrect ip address from 192.168.1.55 to 192.168.0.55, and save the file.

Opatch will now display expected output:

[oracle@lx01 ~]$ opatch lsinventory
Oracle Interim Patch Installer version 11.2.0.3.11
Copyright (c) 2015, Oracle Corporation.  All rights reserved.


Oracle Home       : /u01/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/oraInventory
   from           : /u01/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version    : 11.2.0.3.11
OUI version       : 11.2.0.1.0
Log file location : /u01/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-09-02_09-07-43AM_1.log

Lsinventory Output file location : /u01/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/lsinv/lsinventory2015-09-02_09-07-43AM.txt

--------------------------------------------------------------------------------
Local Machine Information::
Hostname: lx01.oric.no
ARU platform id: 226
ARU platform description:: Linux x86-64

Installed Top-level Products (1): 

Oracle Database 11g                                                  11.2.0.1.0
There are 1 products installed in this Oracle Home.


There are no Interim patches installed in this Oracle Home.


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

OPatch succeeded.

How to solve: error while loading shared libraries: libaio.so.1: cannot open shared object file: No such file or directory

After a fresh install of an Oracle 32-bit client on a 64-bit Linux server, we received the following errors when we tried to use any of the binaries under the $ORACLE_CLIENT_HOME/bin directory:

 error while loading shared libraries: libaio.so.1: cannot open shared object file: No such file or directory

It turned out that only the 64-bit version of libaio was installed:

yum list libaio
Loaded plugins: product-id, rhnplugin, security
This system is receiving updates from RHN Classic or RHN Satellite.
Installed Packages
libaio.x86_64  0.3.107-10.el6  @anaconda-RedHatEnterpriseLinux-201301301459.x86_64/6.4
Available Packages
libaio.i686  0.3.107-10.el6  prod-rhel-x86_64-server-6

Solution is to simply install the missing package (output abbreviated):

su -
yum install libaio.i686

downloading Packages:
libaio-0.3.107-10.el6.i686.rpm                                                                                                                                                                    |  21 kB     00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing : libaio-0.3.107-10.el6.i686                                                                                                                                                                            1/1
  Verifying  : libaio-0.3.107-10.el6.i686                                                                                                                                                                            1/1

Installed:
  libaio.i686 0:0.3.107-10.el6

Complete!

How to create a symlink in unix

Syntax:
ln -s /path/physical_file symlink

For example

cd $ORACLE_HOME/lib
ln -s /u01/oracle/product/oracle_client32/lib/libclntsh.so.11.1 libclntsh.so
ls -altr libclntsh.so
libclntsh.so -> /u01/oracle/product/oracle_client32/lib/libclntsh.so.11.1