Oracle VM Server: Pool is locked forever

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 other change would do the job, but this is a minimal change, which solves the problem...

Hopefully there will be an update, so this problem will disappear in future versions.


Microsofts Visual Studio Code on Linux

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 https://code.visualstudio.com/ 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 - less a second.

Within Visual Studio Code it is very easy to install some extensions:

Running a small javascript program is very easy. I just entered these lines and without any further configuration running the program or debugging was no problem:


Linux ser2net: no connection to /dev/ttyUSB0

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 NONE 1STOPBIT 
This means: on port tcp 15000 you can access the serial port /dev/ttyUSB0 (if you have a USB to serial adapter in place).

If this does not work, check the ports with
root@ubuntu:/home/ubuntu/dfld# netstat -lntup |grep ser2net
tcp6       0      0 :::15000                :::*                    LISTEN      1361/ser2net        
As you can see, it only listens on TCP6. So you have to reconfigure this to,15000:raw:0:/dev/ttyUSB0:9600 8DATABITS NONE 1STOPBIT
If you only want to access this on localhost (which is very nice security enhancement ;-) ).
And after a restart of ser2net everything works like expected:

root@ubuntu:/home/ubuntu/dfld# netstat -lntup |grep ser2net

tcp        0      0*               LISTEN      


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

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 i wanted to move to a raspberry pi. But this runs on ARM and the RXTX is only provided for x86/x64 systems.

But there is another way: ser2net

With this proxy /dev/ttyUSB0 can be mapped to a tcp port and java can access this without using RXTX.


Alpine Linux, Oracle Java JDK and musl?! - why it does not work...

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 dfld.de) 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 /dev/ttyUSB0.

What is the problem with this setup?
  • RXTX needs a Java which is running on glibc
  • Alpine Linux does not run on glibc
If you are not aware of this problem, you get some errors like
./javaash: java: command not found
and this happens even if you are in the right directory and java got the execute bit configured.

Alpine Linux changed to musl:
There are some other libc implementations (take a look here).
The homepage is https://www.musl-libc.org/:

 And a comparison to other libc can be found at http://www.etalabs.net/compare_libcs.html:

There are some workarounds to get applications build with glibc running on Alpine Linux, but i did not get to run my aircraft noise measuring station - i switched to Debian - because i needed a 32bit Linux for my very old UMPC...


Oracle Cloud: Feature Set

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 Administration
    • Account Management
    • Identity
Inside the Compute item the following services can be found:
  • Compute
    • Instances
    • Dedicated Virtual Hosts
    • Instance Configurations
    • Cluster Networks
    • Autoscaling Configurations
    • Custom Images
    • Boot Volumes
    • Boot Volume Backups
  • Block Storage
    • Block Volumes
    • Block Volume Backups
    • Volumes Groups
    • Volume Group Backups
  • Object Storage
    • Object Storage
    • Data Transfer
  • File Storage
    • File Systems
    • Mount Targets
  • Networking
    • Virtual Cloud Networks
    • Dynamic Routing Gateways
    • Customer-Premises Equipments
    • IPSec Connections
    • Load Balancers
    • FastConnect
    • Public IPs
    • DNS Zone Management
    • Traffic Management Steering Policies

  • Administration
    • Tenancy Details
    • Announcements

The menu Database has no subitems.

For most of these services you can find documentation here:


Oracle cloud: Login

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

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  486M   0% /sys/fs/cgroup
/dev/sda3        39G  1,9G   37G   5% /
/dev/sda1       200M  9,7M  191M   5% /boot/efi
tmpfs            98M     0   98M   0% /run/user/1000
[opc@myVmInstanceDS ~]$ 


Oracle cloud: sign up: after nearly 2 weeks...

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:

With the next postings i will try to get some VMs etc. running inside Oracle Cloud...


500 blog posts (in 12 years)

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

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 credit card (then i should see it).
Or is this process buggy and i was for some reason not charged?
Or is re-authorization something else?


Oracle Cloud: First login

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

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]

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.


There is a tiny link "click here" just abouve the blue button. This link a have to use with the verification code provided by Oracle support.
But then the error is:
I checked this a VISA and MASTERCARD. Neither of them worked...

UPDATE 2: see here how the problem was solved.


Oracle Cloud: Sign up failed...

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 following error:

"We're unable to process your transaction. Please contact Oracle Customer Service."
The link "Oracle Customer Service" did not work, so i used the Chat Support. But inside the chat was no agent available and only "Send E-Mail" worked. Let's see what kind of response i will be given...

EDIT: Some further attempts...

EDIT 2: see here how the problem was solved.