Dec 4, 2018

CassandraRoleManager skipped default role setup: some nodes were not ready


I had this issue with my Cassandra 3.11.3 cluster.
'CassandraRoleManager skipped default role setup: some nodes were not ready'

Actually i didn't raised one of my nodes. The status was:

Datacenter: datacenter1
|/ State=Normal/Leaving/Joining/Moving
--  Address        Load       Tokens       Owns (effective)  Host ID                               Rack
UN  X.X.15.141  279.12 KiB  256          49.1%             65b80558-219d-478b-ad24-083a79d78348  rack1
UN  X.X.15.140  235.39 KiB  256          49.2%             0efb432f-0789-455f-op24-29c6e2cce9ac  rack1
UN  X.X.15.142  287.49 KiB  256          49.6%             3558e3f0-717d-783UI-a22c-6891a3bd427f  rack1
DN  X.X.15.144  ?          256          52.2%             8e8cdbac-9088-3421-963d-4857a78087d3  rack1

To solve it, i used the nodetool with 'removenode' method. Reference

Removing this node solved the problem for me.


Aug 7, 2018

Refusing to serve hidden directory, via 404 Error on AWS EC2

Refusing to serve hidden directory, via 404 Error

I got this error while running jupyter notebook inside my EC2

My Solution --> when i first run it, i was inside .jupyter directory.

I created my own 'workspace' directory, switching into it and then run it again the 'jupyter notbook'

Now all ok.

Hoped it helped,


Jun 6, 2017

Openstack using DevStack - Failed to fetch cdrom


While going over all the configuration needed with devstack for open stack and during the installation - after running ./ i received an error
"failed to fetch cdrom ...."

To solve this, go into /etc/apt
do 'sudo nano sources.list' and remove by using '#" the cd rom line.

Then start again the ./ and it will work

you just removed / disabled the cd rom

Hoped i helped,

Apr 27, 2017

Parameter CONFIG_CONTROLLER_HOST failed validation: Given host does not listen on port 22:

Hi ,

Happen to me during openstack installation on fedora 25.

Solution - start the sshd service

'sudo service sshd start'

Solved for me

Hoped it helps

Jul 25, 2016

ODroid c2 LibreElec

Hi All,

I bought the Odroid c2, wonderful piece of electronic. I bought it with ubuntu.
But once it came and after it requested to update and upgrade --> nothing works.
Then i tried manualy to install the ubuntu again it requested updates --> nothing works.
Then i tried the parallel version to the open elec i have on my pi 2, named also as Libre Elec.
This works good.


Sep 25, 2015

Oracle ORA-28000 Account is locked

Hi All,

This was the solution for me

su - oracle

sqlplus "/ as sysdba"

sql> alter user system account unlock;

--> System was my locked user, in your case replace system with you locked account user name. 

Hope it helped,


Sep 22, 2015

Fedora 22 VirtualBox


I have installed the latest fedora 22 and from some reason VirtualBox gave me tons of errors.

Looked all over the place and didn't find any good solution till now. So i wanted to share this with you to save you time, hopefully that you are seeing before all the searches i already did.

This is the required things to do:
This was my error

WARNING: The vboxdrv kernel module is not loaded. Either there is no module
         available for the current kernel (4.1.6-201.fc22.x86_64) or it failed to
         load. Please recompile the kernel module and install it by

           sudo /etc/init.d/vboxdrv setup

         You will not be able to start VMs until this problem is fixed.

 First , try to run this, with or without sudo
"/etc/init.d/vboxdrv setup"

if it went ok -> you are all good, probably virtualbox will run ok for you, for me it didn't helped.

If it didn't went ok, go over here :
I got this error
Stopping VirtualBox kernel modules                         [  OK  ]
Recompiling VirtualBox kernel modules/etc/init.d/vboxdrv: line 335: /var/log/vbox-install.log: Permission denied
  (Look at /var/log/vbox-install.log to find out what went wrong)

So i did as they say : "cat /var/log/vbox-install.log"
And got this:
Makefile:185: *** Error: unable to find the sources of your current Linux kernel. Specify KERN_DIR=<directory> and run Make again.  Stop.

So i did the following:
"sudo usermod -a -G vboxusers username" (you will replace username with your name of the user)
"su -"
" KERN_DIR=/usr/src/kernels/username" (replace username with your name of the user)
"export KERN_DIR"
"dnf install open-vm-tools"
"dnf -y install kernel-devel kernel-headers"
"sudo /etc/init.d/vboxdrv setup" -> this should be running ok now
You should receive something like me
Stopping VirtualBox kernel modules                         [  OK  ]
Recompiling VirtualBox kernel modules                      [  OK  ]
Starting VirtualBox kernel modules                         [  OK  ]

Good luck and hopefully that i helped a bit,