I have been trying to run VBoxManage.exe from the Windows Task Scheduler to periodically list vms. The problem I had was that it wouldn’t list the VM’s I had registered, even if the task was run as the user that created the VM’s and with the ‘Run with highest privileges’ selected.

When searching the Internet, I saw more people having difficulties running it this way, so I started experimenting. Using ‘psexec‘ and ‘runas’ (use the /savecred option and run it once manually from command line) did work when running the VBoxManage.exe as the VM’s creator user while being logged as someone else, but running it from the Task Scheduler still did not work.

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I recently updated to Internet Explorer 10 (Windows 7 64bit) and when I browsed to a website with a security certificate problem: “There is a problem with this website’s security certificate.”, the “Continue to this website (not recommended).” option was missing!!!

The issue here is that Microsoft restricted access to pages which are using a key using less than 1024 bits for protection. Some Oracle product using websites (including Oracle VM Manager) are still using this!

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SQL> alter database force logging;

ORA-12920: database is already in force logging mode

Error in Dutch:

ORA-12920: Database staat al niet in de force logging-modus.

The word ‘niet’ should not be there!

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I’m talking about the ‘third’ field in the database entries. Field number three. Which indicates there could be a fourth, fifth etc… right?

A customer where I came (who went from AIX to Linux), who had interpreted this comment and therefore expanded the oratab with an extra column, to datapump the database (y/n).

When I shut down the databases, there was some unexpected behaviour when I invoked dbshut… Strange, but the extra (last) field ‘for datapump’ was read, not the third!

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I had a virtual machine in VirtualBox for an OracleVM Server to test an OracleVM setup, but it froze every 5 minutes and had to restart the OVS again and again.

I got this tip from Robert Pastijn, Oracle Netherlands; When you create a virtual machine in VirtualBox for OracleVM Server, do _not_ choose the ‘Intel PRO’ type adapter type, but the ‘PCnet-FAST‘ one!

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There is a bug in Red Hat Linux 6 and Oracle Enterprise Linux 6 (UEK and RHEL-kernel) and probably all other Red Hat 6 related Linux Distro’s.

When you need more memory for SGA/PGA when using MEMORY_MAX_TARGET, you need to resize /dev/shm. By default this is 50% of total memory and Oracle tells you to add the following to /etc/fstab:

shmfs /dev/shm tmpfs size=3g 0 0

Which works…

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A couple of days ago I did a new install of the Oracle Database Software (on a Virtual Machine) and it kept failing. I got some oracle.cluster.verification.VerificationException error, but I could not get more information from the logs. Usually it’s a bit more detailed after the colon, but this time it just said: hostname: hostname.

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Using partitions may decrease search time when searching through a lot of data from minutes to seconds, from hours to minutes. Storing information partitioned per month/year and retrieving it knowing which month/year you want from millions of records is more efficient than an index on all those months and years. Unfortunately changing to partitions afterwards almost always needs application changes, (I actually never tried an sql_profile…).

When looking for a solution using partitioning, I came across another problem. They were using a function in the one and only predicate in the query and the fact is that when a database uses partitioning for storing data, using a function on the partitioned column will the optimizer searching all data, not the partition. Understandable, because with the function you are searching for derived values, not the actual values in the partition. Oracle must search all the partitions and can not ‘prune’ the partitions. Determining and using a partition is called Partition Pruning.

The solution to be used here is called Virtual Column Partitioning and as a coincidence and nice extra they didn’t even had to change the application!

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You can update your Oracle VM Servers with the Oracle Public Yum Server. In the Oracle VM Manager console go to the ‘Tools and Resources’ tab and click ‘Server Update Management (YUM)’.

For the ‘YUM Base URL:’, use:
http://public-yum.oracle.com/repo/OracleVM/OVM3/latest/x86_64/

When enabling the GPG key, use:
http://public-yum.oracle.com/RPM-GPG-KEY-oracle-el5
(Oracle VM is based on OEL5)

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In Oracle Linux 6, it looks like the ‘oracle-validated’ package is missing, but Oracle actually renamed it to ‘oracle-rdbms-server-11gR2-preinstall.x86_64‘.

To quickly use the public yum repository of Oracle and install ‘oracle-rdbms-server-11gR2-preinstall.x86_64′:

cd /etc/yum.repos.d
wget http://public-yum.oracle.com/public-yum-ol6.repo
#vi /etc/yum.repos.d/public-yum-ol6.repo
yum clean all
yum repolist
yum install oracle-rdbms-server-11gR2-preinstall.x86_64

You will get the ‘latest’ build enabled.
If you don’t want this, vi /etc/yum.repos.d/public-yum-ol6.repo .

Happy installing!