Tag Archive: oracle vm repository

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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With the introduction of OCFS2 1.4 within Oracle VM 2.2, Oracle VM 2.2 has the ability to thin provision your files within your OCFS2 filesystem via the use of the sparse files. One might ask, what exactly is a sparse file? A sparse file is a file that attempts to use filesystem space more efficiently by effectively only using the space required to fit actual data. For example, imagine I have a System.img file within my Oracle VM repository that is 6.2GB in size as seen here:

[root@ovm]# ls -llh System.img
-rw-r--r-- 1 root root 6.2G Apr 14 09:18 System.img

If I did not have the sparse file feature within my Oracle VM 2.2 operating system, the  System.img file would actually take up 6.2GB of allocated space away from my OVS repository. However, with the introduction of sparse files to OCFS2 1.4, the actual data contained within  my System.img  was only 3.3GB as shown below. A total savings of 47% of actual diskspace!

[root@ovm]# ls -lsh System.img
3.3G -rw-r--r-- 1 root root 6.2G Apr 14 09:18 System.img

Now that we understand the huge advantages of enabling sparse files, I will show you how to enable sparse files for your Oracle VM 2.2 environment.

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