Lab Correction

Anyone using the August 2018 Fedora image should note that I neglected to put the right transaction_upload2.csv file in the /u01/app/oracle/upload directory. You can fix that by navigating to the Lab 12 Instructions web page and click on the zip file link to download the correct file. You will see the following dialog asking whether you want to open the file with the Ark utility, click OK to continue:

After clicking OK to open (more...)

opatch investigations

This blogpost is about opatch and how to obtain information about the current oracle home(s), and how to obtain information about the patches to be applied.

Patches that can be applied using opatch are provided by oracle as zip files which have the following naming convention:
p[patchnumber]_[baseversion]_[platform]-[architecture].zip. The patch normally contains an XML file called ‘PatchSearch.xml’ and a directory with the patch number. Inside the patch number directory there is a README.txt (more...)

Oracle Database 18c: Installation via rpm (without

Three months after writing the post Where to find the oracle-database-ee-18c-1.0-1.x86_64.rpm package? Oracle released the rpms on their download page:

So let's give it a try.

First thing is to install the prerequisites:
# yum install oracle-database-preinstall-18c

Package Arch Version Paketquelle Größe
oracle-database-preinstall-18c x86_64 1.0-1.el7 ol7_latest 18 k
Als Abhängigkeiten installiert:
bc x86_64 1.06.95-13.el7 ol7_latest 114 k
bind-libs x86_64 32:9. (more...)

jconsole/visualvm/java applications without fonts over ssh forwarding (characters displayed as boxes)

On servers which run java applications sometimes you need to run jconsole or jvisualvm.
This is typically no problem - ssh -X and you are done.

But in some rare circumstances you will get something like this:


Following some other sources, you end up with tweaking xorg parameter without any success. The solution is very easy:
apt-get install ttf-dejavu
And then:

Oracle wait event ‘TCP Socket (KGAS)’

I was asked some time ago what the Oracle database event ‘TCP socket (KGAS)’ means. This blogpost is a deep dive into what this event times in Oracle database

This event is not normally seen, only when TCP connections are initiated from the database using packages like UTL_TCP, UTL_SMTP and the one used in this article, UTL_HTTP.

A very basic explanation is this event times the time that a database (more...)

Enable X11 on Oracle Cloud Infrastructure

Today my colleague was starting with the installation of Oracle Database on the Oracle Cloud Infrastrcture, for a customer. He phoned me for help on enabling VNC to have a graphical UI to install the database.

Install an ssh client with XServer emulator

Most of my co-workers of around my age, have grown up with Putty. And apparently we as computer consultants are quite hooked to our tools. I know, only yesterday I mentioned it (more...)

Java: Slow java with server.policy enabled – how to fix this issue

If you use Java security manager for hardening your java processes, you have to add the following JVM options: 
Create a server.policy file (you can use jdkXXX/jre/lib/security/java.policy as a tamplate) and add the following line:
permission "localhost:*", "listen, accept, connect, resolve"; 
Now create a small java program, which listens on a port (like this example).

If you send a message with netcat

Resolving Slow Performance, Skipped Checks and Timeouts on Exa Check (exachk)


For more information with regards to Exa Check, please read the following post:
How to use Oracle Exadata Database Machine Exa Check (exachk)

Slow Performance, Skipped Checks and Timeouts

When running the latest exachk (at time of writing, version 18.3.0_20180808), you may notice it takes a long time to run compared to the past.  This is due to the vast amount of additional checks carried out by the tool.  Due to (more...)

Repairing a Linux host with disk/filesystem issues

This is a writeup on some scenario’s for disk issues that you could encounter when running linux systems. The linux systems I am talking about are centos/redhat/oracle (EL) version 7 systems. This is just a writeup for myself to know how to deal with different scenario’s, hopefully other people find this interesting too. I don’t believe there is any difference for the below scenario’s and resolutions between running physical/bare metal, virtualised or in the cloud, (more...)

Linux: journalctl and systemd – better than /var/log/messages?

Nearly 8 years ago systemd was introduced on some Linux distribution (s. here). Last week i discovered some helpful commands, which i share with you.

If you want to take a look at kernel message (for example system boot), you command is
The new equivalent is
journalctl -k
Ok - not really amazing.
But all of you know the message
See "systemctl status nginx.service" and "journalctl -xe" for details.
You can run (more...)

Missing directory in /var/run or /run – tmpfiles.d

Sometimes is happens, that an application/demon refuses to start because of missing files/directories in /var/run.
The first solution is:
  • Create the directory in /var/run
  • Change the permissions
and everything is fine.

Not really.

After the next reboot, the directory is missing again and you have to go for the "first" solution again.

The right solution works like this:
Inside /usr/lib/tmpfiles.d create a myexample.conf file with this content:
        d /var/run/myexample  (more...)

Extending the root LVM Partition on Exadata

On an Oracle Exadata Database Machine, the ‘/’ (root) is defaulted to a size of 30Gb, which can easily fill up.  Luckily this is just a Logical Volume and there’s normally lots of space available on the Logical Volume Group which is usually untapped.

Extending ‘/’

Identify how much space is used and free on ‘/’ using df:

[root@v1ex1dbadm01 ~]# df -h /
Filesystem            Size  Used Avail Use% Mounted on
                       30G   22G   (more...)

Oracle Database Backup Service Fails with: ORA-19511: – KBHS-00715: HTTP error occurred ‘oracle-error’ – ORA-29024

I discovered an Oracle Cloud Database Backup failing with:

Starting backup at 2018/09/08 20:00:04
current log archived
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03002: failure of backup plus archivelog command at 09/08/2018 20:00:07
ORA-19554: error allocating device, device type: SBT_TAPE, device name:
ORA-27023: skgfqsbi: media manager protocol error
ORA-19511: non RMAN, but media manager or vendor specific failure, error text:
   KBHS-00715: HTTP error occurred 'oracle-error'
KBHS-00712: ORA-29024  (more...)

Docker on Oracle Linux

It occurred to me that if you want to start using Docker there are plenty examples that use Ubuntu as a base platform. I read a book called Learning Docker that assumes Ubuntu for the examples. I know I am quite stubborn, a "know-it-better" person, but I want to be able to do the same on Oracle Linux.

Docker on Oracle Linux turns out not too complicated. But I ran in to a caveat that (more...)

systemd: systemd-notify not working for non-root-users

Sometimes you have to write your own startup scripts. Recent linux distributions require systemd scripts. This is not really a problem except you have to fulfill the following requirements:
  • Run the service as a non-root-user
  • The service has a startup phase and you want to start the next startup scripts after this startup phase
So the systemd-script has to look like this:
# cat /lib/systemd/system/TEST.service

The (more...)

Ubuntu / Linux: WLAN connections fails with "denied authentication (status 17)"

During holidays i was not able to connect my laptop to the WLAN.
The /var/log/syslog showed the following:
Jul 15 13:45:20 pc wpa_supplicant[935]: wlp3s0: SME: Trying to authenticate with 14:9d:09:fe:a4:b3 (SSID='HUAWEI BTV' freq=2437 MHz)
Jul 15 13:45:20 pc kernel: [ 6972.826888] wlp3s0: authenticate with 14:9d:09:fe:a4:b3
Jul 15 13:45:20 pc NetworkManager[797]:   [1531655120.4746] device (wlp3s0): supplicant interface state: disconnected -> authenticating
Jul 15 13:45:20 pc kernel: [ 6972.829942] wlp3s0: send auth to 14:9d:09:fe:a4:b3 (more...)

Oracle Database 18c: Documentation released!

Today i surfed to and there i found the documentation for oracle database 18c:

In march 2018 i wrote about the new installation procedure of oracle database 18c via rpm, which was announced inside the "new features".

The installation guide for Linux contains now the commands for installing the database via rpm. Here a screencopy of chapter 11:
 rpm -ivh oracle-ee-db-
This command creates the (more...)

Ubuntu 16.04: Installation of chrome-browser fails with libnss3 (>= 2:3.22) [2]

The first solution for installing google-chrome after getting the error
dpkg: Abhängigkeitsprobleme verhindern Konfiguration von google-chrome-stable:
 google-chrome-stable hängt ab von libnss3 (>= 2:3.22); aber:
  Version von libnss3:amd64 auf dem System ist 2:3.21-1ubuntu4.

dpkg: Fehler beim Bearbeiten des Paketes google-chrome-stable (--install):
 Abhängigkeitsprobleme - verbleibt unkonfiguriert
was to install chromium (see this posting).

But now i know, what the problem was:
Inside /etc/apt/sources.list the entry:
deb xenial-security restricted main (more...)

Quick install of prometheus, node_exporter and grafana

This blogpost is a follow up of this blogpost, with the exception that the install method in this blogpost is way easier, it uses an Ansible playbook to do most of the installation.

1. Install git and ansible via EPEL:

# yum -y localinstall
# yum -y install ansible git

2. Clone my ‘prometheus_node_exp_grafana_install’ repository:

# git clone

3. Run the prometheus.yml playbook to install (more...)

Virtualbox: failed & Run ‘make oldconfig && make prepare’

After updating to ubuntu 18.04 i had to reinstall virtualbox:

# dpkg -i virtualbox-5.2_5.2.10-122088~Debian~stretch_amd64.deb 
Vormals nicht ausgewähltes Paket virtualbox-5.2 wird gewählt.
(Lese Datenbank ... 378316 Dateien und Verzeichnisse sind derzeit installiert.)
Vorbereitung zum Entpacken von virtualbox-5.2_5.2.10-122088~Debian~stretch_amd64.deb ...
Entpacken von virtualbox-5.2 (5.2.10-122088~Debian~stretch) ...
virtualbox-5.2 (5.2.10-122088~Debian~stretch) wird eingerichtet ...
addgroup: Die Gruppe »vboxusers« existiert bereits als Systemgruppe. Programmende. failed: Look at /var/log/vbox-install. (more...)