Oracle Linux 6 Implementation Essentials

Network bonding refers to the combination of network interfaces on one host for redundancy and/or increased throughput.

* Use the sar -q command to report the following information:

The Average queue length while the queue is occupied.

The percentage of time that the queue is occupied.

* The following list describes the output from the -q option.

runq-sz
The number of kernel threads in memory that are waiting for a CPU to run. Typically, this value should be less than 2. Consistently higher values mean that the system might be CPU-bound.

%runocc
The percentage of time that the dispatch queues are occupied.

swpq-sz
Swap queue of processes for the sar command.
%swpocc
Swap queue of processes for the sar command.

Example:
Create a yum .repo file:
cd /etc/yum.repos.d cat > ol63iso.repo << EOF
[ol6_base_media]
name=Oracle Linux 6 Media
baseurl=file:///mnt/iso/ol63/Server gpgcheck=0
enabled=1
EOF
#

Incorrect:
Not B: Specifiy the directory, not the iso file name.
Not C: Enabled should be 0, not 1.
Not D: Use file: not http: to specify the directory

C: Ether parameter:
The most common use of this parameter is to force probing for a second ethercard, as the default is to only probe for one (with 2.4 and older kernels). This can be accomplished with a simple: ether=0,0,eth1

Note:
* rhgb stands for redhat graphical boot. This is a GUI mode booting screen with most of the information
hidden.
* quiet parameter hides the majority of the boot messages before rhgb starts.

Example:
options netconsole [email protected]/eth0,[email protected]/00:1A:A0:D2:55:66

6666 => Server source port
10.0.0.1 => Server IP
eth0 => Server NIC
514 => Client listening port
10.0.0.2 => Client IP 00:1A:A0:D2:55:66 => Client MAC

* The command rpm -q --changelog rpm displays a detailed list of information (updates, configuration, modifications, etc.) about a specific package. This example shows information about the package rpm.
However, only the last five change entries in the RPM database are listed. All entries (dating back the last two years) are included in the package itself. This query only works if CD 1 is mounted at /media/cdrom:

rpm -qp --changelog /media/cdrom/suse/i586/rpm-3*.rpm

* Is the patch RPM suitable for my system?

To check this, first query the installed version of the package. For pine, this can be done with rpm -q pine
pine-4.44-188

Incorrect:
not C:

* qa stands for "Query All"
Assuming you are attempting to find out if you have the Very Secure FTP Daemon installed, you want:
rpm -qa | grep vsftp
rpm -qa will show you all installed RPMs, piping it through grep will limit the list to RPMs containing the string "vsftp".

installonly_limit

Number of packages listed in installonlypkgs to keep installed at the same time. Setting to 0 disables this feature. Default is '3'. Note that this functionality used to be in the "installonlyn" plugin, where this option was altered via. tokeep. Note that as of version 3.2.24, yum will now look in the yumdb for a installonly attribute on installed packages. If that attribute is "keep", then they will never be removed.

References:
yum.conf

A configuration file exists for the purpose of persisting changes, named /etc/sysct1.conf. When booting, your server starts the procps service that reads this configuration file and applies all settings in it.

Note:
* If you've ever needed to change the hostname for Red Hat Linux, CentOS or similar operating systems, you can do so easily with one simple command.

Just use the echo command to replace the contents of /proc/sys/kernel/hostname with your new host name.
# echo hostname.com > /proc/sys/kernel/hostname
Then restart the network interfaces:

# /etc/init.d/network restart
Shutting down interface venet0: [ OK ]
Shutting down loopback interface: [ OK ]

Bringing up loopback interface: [ OK ]
Bringing up interface venet0: RTNETLINK answers: File exists RTNETLINK answers: File exists
[ OK ]
Now you can use the hostname command to verify that it has changed.

* Commercial technical support is available through Oracle's Oracle Linux Support program, which supports Oracle Linux, and existing RHEL or CentOS installations (i.e. without reinstallation).

Note:
* The Unbreakable Enterprise Kernel Release 2 is Oracle's second major release of its heavily tested and optimized operating system kernel for Oracle Linux 5 and Oracle Linux 6. Unbreakable Enterprise Kernel Release 2 is based on the mainline Linux kernel version 3.0.16 and boasts a wide range of new features and improvements relevant for enterprise workloads.

Incorrect:
Not A, not B: Unbreakable Enterprise Kernel Release 2 can be installed on Oracle Linux 5 Update 8 or newer, as well as on Oracle Linux 6 Update 2 or newer.

Package Selection Options include:
-f <file>

Query package owning <file>

Note:
rpm -q -- What does it do?
One of the nice things about using RPM is that the packages you manage don't end up going into some kind of black hole. Nothing would be worse than to install, upgrade, and erase several different packages and not have a clue as to what's on your system. In fact, RPM's query function can help you get out of sticky situations like:

* You're poking around your system, and you come across a file that you just can't identify.
Where did it come from?

* Your friend sends you a package file, and you have no idea what the package does, what it installs, or where it originally came from.

* You know that you installed XFree86 a couple months ago, but you don't know what version, and you can't find any documentation on it.

The list could go on, but you get the idea. The rpm -q command is what you need. If you're the kind of person that doesn't like to have more options than you know what to do with, rpm -q might look imposing.
But fear not. Once you have a handle on the basic structure of an RPM query, it'll be a piece of cake.