Oracle VM Server: Pool is locked forever

| Dec 23, 2019
If you are using Oracle VM Server it is possible that you are hitting the following problem:

After changing something on a server pool the pool gets locked and the lock stays there:
Even a reboot of your OVMM (oracle vm manager) does not remove the lock.

The solution can be very easy:
Just edit the pool and add (or change) the description.

This edit triggers an update and removes the lock. I think every (more...)

Microsofts Visual Studio Code on Linux

| Dec 10, 2019
On the last weekend i was wondering, what kind of IDE i can use for doing some small programs with javascript. My first idea was eclipse, but a friend mentioned Microsofts Visual Studio Code:
 So i opened and got
So i downloaded the .deb and after a dpkg -i of that file i was able to run Visual Studio Code on my Linux machine:
schroff@zerberus:~$ code 
The startup was amazing fast - (more...)

Linux ser2net: no connection to /dev/ttyUSB0

| Dec 1, 2019
If you are running some java application on a Linux box (especially ARM architecture) and this application accesses the serial interface (/dev/ttyUSB0, /dev/ttyUSB1 or just /dev/ttyX), then a easy way to do this, is running ser2net.

For all who are not familiar with the serial port:

But there is one tricky thing, you have to consider when using ser2net:

Inside ser2net.conf you will find some lines like this here:

15000:raw:0:/dev/ttyUSB0:9600 8DATABITS (more...)

How to run a java software which needs RXTX on a raspberry pi

| Nov 23, 2019
In my last posting i wrote about migrating my aircraft noise measurement station to alpine linux. There i had some problems with getting the RXTX library for Java running on a linux, which uses musl and not GNU libc6.

Why does my java application require RXTX? As stated on the RXTX page:
RXTX is a Java library, using a native implementation (via JNI), providing serial and parallel communication for the Java Development Toolkit (JDK).
Now (more...)

Alpine Linux, Oracle Java JDK and musl?! – why it does not work…

| Nov 17, 2019
Sometime ago i did some work with Alpine Linux (s. here) and i was impressed how tiny this Linux distro was and how fast it was running.

So i decided after nearly 6 years of running an aircraft noise measuring station (for with Ubuntu to change to Alpine Linux.

This station runs a software on Java and needs RXTX, because the microphone is connected via USB and is read over (more...)

Oracle Cloud: Feature Set

| Nov 10, 2019
For all readers, who want to get a short overview to the services which can be configured inside Oracle Cloud, here a walkthrough the menus.
The Main menu shows the following items:
  • Core infrastructure
  • Compute
  • Block Storage
  • Object Storage
  • File Storage
  • Networking 
  • Database
    • Bare Metal, VM, and Exadata
    • Autonomous Data Warehouse
    • Autonomous Transaction Processing
    • Data Sale
    • Exadata Cloud Connector
  • Solution and Patterns
    • Analytics
    • Resource Manager
    • Email Delivery
    • Application Integration
    • Monitoring
    • Developer Services Marketplace
  • Governance and (more...)
  • Oracle cloud: Login

    | Oct 11, 2019
    Main problem for login into Oracle cloud is to there is no generic login URL.
    Inside the mail Oracle sent after the registration there is a specific URL. Something like:
    But this ends after some seconds at:

    There is also another login page, but this one does not work for my setup:

    For this one i did not find any documentation at all, so i somebody knows how this login page can be used, please add a comment...

    Oracle Cloud: my first VM

    | Oct 1, 2019
    After some problems with signing up i created my first vm inside Oracle Cloud:

     and then a short stop for provisioning:

     And finally:

    The machine runs and a login can be done with:

    schroff@zerberus:~/.ssh$ ssh -l opc
    [opc@myVmInstanceDS ~]$ df -h
    Filesystem      Size  Used Avail Use% Mounted on
    devtmpfs        459M     0  459M   0% /dev
    tmpfs           486M     0  486M   0% /dev/shm
    tmpfs           486M   13M  473M   3% /run
    tmpfs           486M     0  (more...)

    Oracle cloud: sign up: after nearly 2 weeks…

    | Sep 27, 2019
    After trying to get around my problems with my
    i was able to sign up at Oracle cloud services.
    Thanks to Oracle support for the e-mails with tips and explanations what i have to do!

    And after some seconds i got the following e-mail:

    And the sign in worked:


    500 blog posts (in 12 years)

    | Sep 24, 2019
    Last week i did my 500th posting - not really "run like hell" but i think better than nothing.
    Here some statistics:

    I think, i will continue for another 500. The exciting point is, wether i will find enough topics, which i am interested in...

    Oracle Sign up: more problems

    | Sep 13, 2019
    I thought, i was successful, but:

    I received a mail with the following content:

    "We have re-authorized a new, specific amount on the credit/debit card used during the sign up process."


    "To verify the account you have created, please confirm the specific amount re-authorized."

    My problem: there is not any "re-authorized amount" on my banking account. I do not know, what is "re-authorized"?
    Is this: this amount is charged on my (more...)

    Oracle Cloud: First login

    | Sep 12, 2019
    After signing up to Oracle cloud i tried my first login:

    but i only got:
    I think the problem is, that there i a manual review step on Oracle's side which i have not passed for now:
    So let's wait for a day or two...

    Oracle Cloud: Sign up failed… [3] & solved

    | Sep 10, 2019
    Finally (see my attempts here and here) i was able to sign up to Oracle cloud.
    What did the trick?

    I got help from Oracle support:
    So i used my gmail address and this worked:

    and then:

    Let's see how this cloud will work compared to Azure and AWS

    Oracle Cloud: Sign up failed… [2]

    | Sep 6, 2019
    After my failed registration to Oracle cloud, i got very fast an email from Oracle support with the following requirements:
    So i tried once again with a firefox "private" window - but this failed again.
    Next idea was to use a completely new installed browser: so i tried with a fresh google-chrome.
    But the error still remained:
    Let's hope Oracle support has another thing which will put me onto Oracle cloud.

    Oracle Cloud: Sign up failed…

    | Sep 1, 2019
    Yesterday i tried to sign up for oracle cloud:

     So let's start the registration process:

    The mobile number verification is done with SMS and after entering the 7 digit pin, you are allowed to enter a password:

    As payment information only credit cards are accepted:
    • VISA
    • Mastercard
    • Amex

    Eve though my credit card was accepted:

    "Your credit card has been successfully validated. Please proceed to complete the Sign up."
    I got the (more...)

    Ubuntu Linux: Change from Legacy boot to UEFI boot after installation

    | Aug 31, 2019
    This weekend i did an installation of Linux on a laptop where already a windows 10 was installed.
    Because laptop did not recognize my linux boot usb-stick i changed from UEFI to legacy mode and the installation went through without any problem.

    At the end grub was in place but the windows installation was not listed. This is, because windows does not support booting.

    The problem: If i switch back to UEFI the linux installation (more...)

    Linux: Configuring hosts per ssh in parallel: pssh

    | Aug 16, 2019
    If you have to set up some hosts in a way, that a number of commands has to be executed on each node, than you should consider PSSH:

    The installation is straight forward:
    root@zerberus:~# apt-get install pssh
    Paketlisten werden gelesen... Fertig
    Abhängigkeitsbaum wird aufgebaut.      
    Statusinformationen werden eingelesen.... Fertig
    Die folgenden Pakete wurden automatisch installiert und werden nicht mehr benötigt:
      btrfs-tools geoip-database-extra libcryptui0a libjs-openlayers seahorse-daemon
    Verwenden Sie »apt autoremove«, (more...)

    Oracle VM Server: Why the server uuid is important and why changes to this uuid are critical

    | Aug 4, 2019
    After working a while with Oracle VM server it turns out, that a very important parameter is the UUID of a Oracle VM server.

    This UUID is used by the ovs-agent (take a look at the Oracle documentation). Here a few excerpts of these chapter:
    The Oracle VM Agent is a daemon that runs within dom0 on each Oracle VM Server instance. Its primary role is to facilitate communication between Oracle VM Server and (more...)

    Firefox on Linux: password field flickering / curser blinks…

    | Jul 20, 2019
    After upgrading to firefox 68 i was not able to enter the password (and configuration password) field in online registrations.
    The cursor in the password fields kept flickering/blinking and on some pages firefox completely freezes.
    With other browsers this does not happen, but i wanted to stay with firefox.

    The solution was starting firefox with an additional environment variable:

    GTK_IM_MODULE=xim firefox

    apt-get install aspnetcore-runtime-2.2 fails on ubuntu: workaround with snap

    | Jul 14, 2019
    Two week ago i tried to install a microsoft tool on my linux laptop and i got the following error:
    So i tried:

    apt-get install aspnetcore-runtime-2.2
    Paketlisten werden gelesen... Fertig
    Abhängigkeitsbaum wird aufgebaut.
    Statusinformationen werden eingelesen.... Fertig
    Einige Pakete konnten nicht installiert werden. Das kann bedeuten, dass
    Sie eine unmögliche Situation angefordert haben oder, wenn Sie die
    Unstable-Distribution verwenden, dass einige erforderliche Pakete noch
    nicht erstellt wurden oder Incoming noch nicht verlassen haben.
    Die (more...)