Tag Archive: ovm


When considering an Oracle RAC environment, one of the main questions that always seems to be asked is “How much is Oracle RAC licensing going to cost me?” While Oracle RAC licensing can be expensive, there is a way to cut some of those expenses out by ensuring that the amount of CPUs you are licensing is truly what you need. While attempting to size your physical environment with the correct amount of CPU cores required is possible, it is also very difficult due to vast growth of multi-cored CPUs in the market. A better option would be using Oracle VM to hard partition only the cores required for your Oracle RAC environment. This methodology known as ‘hard partitioning’ allows you to take advantage of Oracle RAC technology and save on Oracle RAC licensing costs.
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In today’s Oracle VM Manager there is no way of extending the disk size of a guest VM. However, via this tutorial I will show you how to extend the .img file.

PLEASE NOTE: It is highly recommended to make a backup of the disktoExtend.img file prior to trying the steps below.

Let us assume we have an Oracle VM guest which contains 3 files. The three files are the following: System.img, disktoExtend.img, and vm.cfg. Our guest VM is running RHEL/OEL.

[root@OVMSERVER]# ll
total 22000640
-rw-r--r-- 1 root root 26847313920 Oct 13 10:28 disktoExtend.img
-rw-r--r-- 1 root root 11630545920 Oct 13 09:57 System.img
-rw-rw-rw- 1 root root 459 Oct 13 10:27 vm.cfg

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Before creating virtual machine, one must create a server pool. Creation of the server pool can be found on my blog via this post or search via my blog  for “Creating a Server Pool via Oracle VM Manager”.

The steps on creating a Virtual Machine are as follows:

1. Select the ‘Virtual Machines’ tab and click ‘Create Virtual Machine’ located on the right corner.

2. Select the appropriate creation method to be used to create your virtual machines. For the purposes of this blog, we will be selecting the ‘Create from installation media’ radio button and click Next.

3. Select the appropriate Server Pool to be used and modify the ‘Preferred Server’ section from Auto to Manual if this particular virtual machine needs to run on a particular server located within your server pool. If not, please leave Auto as the default and click Next.
NOTE: Changing from Auto to Manual will disable high availability for that particular virtual machine, not recommended.

4. Select the appropriate virtualization method for your particular VM. Within our best practice configuration we used the Paravirtualized virtualization method for optimal performance.
NOTE: When using the ‘Fully Virtualized’ method, you must first register and activate your ISO Files located under the Resources -> ISO Files section. The ISO files can be registered using an external source such as HTTP server or you can copy each of your ISO files to the /OVS/iso_pool/<name_of_iso_dir>/ and select the appropriate server pool to discover and register these ISO files.
NOTE: When using the ‘Paravirtualized’ method, please make sure to extract all of the files found within your OS distribution ISOs and place them within your HTTP or FTP server.

5. Enter the virtual machine information with the specifications required for your particular VM and click Next.

6. Verify that the information is correct and click Finish.

Oracle VM uses Oracle VM Server (OVS) repositories to store resources such as virtual machines, templates, ISO images, and shared virtual disks. Once a storage repository has been created and initialized, it will create storage repository directories to store these resources. One of these sub-directories is the running_pool directory which will contain your virtual machines. Via your Server Pool Master you will create an OVS repository following the steps below.

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The Oracle® Cluster File System (OCFS2) is the file system used for setting up the Oracle® VM Server (OVS) repository partition for shared disk access across all your OVM Server nodes. OCFS2 uses a heartbeat mechanism across all your OVM nodes via the network to maintain data consistency.

In order to setup your OCFS2 repository, the setup of the o2cb cluster service must be done on all your OVM Servers. From each node, run the following setup script using the command and insert the following inputs:

service o2cb configure

Load O2CB driver on boot (y/n) [y]: y
Cluster stack backing O2CB [o2cb]: o2cb
Cluster to start on boot (Enter “none” to clear) [ocfs2]: ocfs2
Specify heartbeat dead threshold (>=7) [100]: 100
Specify network idle timeout in ms (>=5000) [30000]: 30000
Specify network keepalive delay in ms (>=1000) [2000]: 2000
Specify network reconnect delay in ms (>=2000) [2000]: 2000

 Oracle VM’s architecture provides the same native bonding module that is found in all Enterprise Linux 5.x distributions. Although bonding has several different modes which include modes such as the round robin policy and load balancing policy, the active-backup policy (mode 1) is the preferred mode for Oracle RAC interconnects. The active-backup policy has only one active slave and the remaining are passive slaves. One of the other slaves will become active, if and only if, there is a failure with the current active slave within the bond.

In order to setup bonding within the OVM environment, the first step is to stop any guest VMs that are currently running. Once you have stopped all guest VMs, you must stop all network bridges within your OVM environment using the following command

/etc/xen/scripts/./network-bridges stop
 
The network-bridges script controls the creation of your network bridges for each physical NIC. The default behavior of OVM is to create a xen bridge for each physical NIC.
In the following example, we will start configuring our bond0 device and enslave two NIC adapters (eth1 and eth2) to our bond device.

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