23.12.2019

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.


10.12.2019

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:


01.12.2019

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:
https://en.wikipedia.org/wiki/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

127.0.0.1,15000: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      0 127.0.0.1:15000         0.0.0.0:*               LISTEN      

23.11.2019

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.

17.11.2019

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...


10.11.2019

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:
https://docs.cloud.oracle.com/iaas/Content/home.htm




11.10.2019

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:
http://app.response.oracle-mail.com/e/er?elq_mid=920.......
But this ends after some seconds at:

https://cloud.oracle.com/en_US/sign-in


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

https://login.eu-frankfurt-1.oraclecloud.com/v1/oauth2/authorize


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...

01.10.2019

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 130.61.89.226 -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 ~]$ 

27.09.2019

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...

24.09.2019

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...

13.09.2019

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."

and

"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?



12.09.2019

Oracle Cloud: First login

After signing up to Oracle cloud i tried my first login:

https://cloud.oracle.com/en_US/sign-in


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...

10.09.2019

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

06.09.2019

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.

UPDATE:


 
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.

01.09.2019

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.