Update / install Oracle Linux 6.4 corrupts console in Oracle VM 3.x

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After updating Oracle Linux 6.3 to 6.4 or installing 6.4 from scratch will give a corrupt (blank) VNC remote console when launching the console from Oracle VM Manager:

oracle_vm_3_oel_6.4_console

As discussed in https://oss.oracle.com/ol6/docs/RELEASE-NOTES-U4-en.html#idp513536 and Oracle Support note ‘Corrupted VNC console in PVM guests running Oracle Linux 6.4 on Oracle VM’ (Doc ID 1537278.1), this issue is addressed in ‘X Window System Does Not Run in a PVHVM guest’.

Uninstalling the xorg-x11-drv-cirrus guest driver solves the issue

If you uninstall the xorg-x11-cirrus driver from the guest OS, it will solve this issue.

# rpm -ev --nodeps xorg-x11-drv-cirrus

Reboot the guest OS after uninstalling.

Happy Launching!

Remove Oracle Database Options with chopt in 12c

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In 10g and 11g Enterprise Edition, one could select which options to install or not to install during the installation process (excl. the 10g ‘custom database’ option, you would get partioning, OLAP and rat). In 12g, one is not able to choose during install anymore, you will get all the options and they must be removed afterwards. Remove / disable them after installing the database software (only), but before creating databases.

The best way to do this is using the ‘chopt’ tool, or when the option is not available, the Oracle Universal Installer must most likely be used. It’s available in Windows and Linux. When using Windows, one can also rename the .dll’s which ‘enable’ the options. It will NOT remove the objects from the database! Continue reading →

Running VBoxManage.exe from Windows Task Scheduler

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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. Continue reading →

Internet Explorer 10 ‘Continue to this website’ option missing

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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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The oratab usage comment is not correct… or it’s a bug in dbstart/dbshut (sort of)…

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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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Oracle VM Server on Oracle VirtualBox freezes / hangs

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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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Bug: /def/shm does not use /etc/fstab attributes after reboot

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SOLVED: this issue is solved in Linux 6.4 (kernel: 2.6.39-400.17.1.el6uek and 2.6.32-358.el6).
A single entry in /etc/fstab like [tmpfs /dev/shm tmpfs size=3g 0 0] now works as it should!

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, ‘mounting’ the /dev/shm twice (?):

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

Which works…

IMPORTANT NOTE: make sure the first field (fs_spec) ‘shmfs’ or ‘tmpfs’ gets the same name as the already existing ‘defaults’ name. So if you have a line [tmpfs /dev/shm tmpfs defaults 0 0], make sure the ‘overruled’ line also starts with ‘tmpfs’: [tmpfs /dev/shm tmpfs size=3g 0 0].

If not, a `mount -a` will un-mount (!!!) the ‘shmfs’ and remount ‘tmpfs’, this results in immediate clearing the ‘/dev/shm’ memory and all your SGA is instantly gone! Running this when databases are running, your databases with AMM will crash! This ‘issue’ is still there last time checked in Linux 7.3. In Oracle documentation about /dev/shm, the first field is ‘shmfs’ with can result in crashing databases when a `mount -a` done!

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oracle.cluster.verification.VerificationException: [hostname]: [hostname]

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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]. Continue reading →

Partition pruning fails when using functions: use virtual column partitioning

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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! Continue reading →