[clug] OpenStack, Ansible, hypervisors, iSCSI storage & other Clug Topics

George at Clug Clug at goproject.info
Wed Jun 29 12:53:47 UTC 2016


In your talk, you mentioned that you use FreeNAS, I have not as yet
used FreeNAS, I have used OpenFiler for my test environment's iSCSI
server (it works well, but I would believe any iSCSI storage system is
much like another, storage is a reasonably basic function). I use
Openfiler, not for any specific reason, just due to circumstances. If
anyone has experience with both systems or any other Open Source
systems, and wishes to comment, please do. I was thinking of just
using Linux to set up an iSCSI server too, but never quite found the
time, is anyone doing this?

Did you manage to get DevStack's OpenStack to use local storage? so
that there would be no need for a physical network to access external
iSCSI or other storage. This is something that I wanted to do, but
have yet to be successful. It would be great if someone could point me
to helpful instructions.

I have a personal belief that the CPU speed of the host server has a
great effect on the performance of any guest servers, that is a single
CPU with four cores (two threads per core), running at 4 GHz will run
up to four "one virtual CPU" guests faster than two CPUs with 10 cores
(two threads per core), running at 1.8GHz.

Obviously performance decreases drastically if you start running more
virtual CPUs than you have physical cores*threads. That is if you
tried to run 20 virtual CPUs on a single, four core 4GHz CPU host,
each virtual host will perform worse than on a two CPU, 10 Core host
running at 1.8GHz.

What I am trying to say, unless your guest virtual machine and its
application software can effectively utilise multi-threading, the CPU
speed of the host plays a significant part on the performance of the
guest virtual machines.

If anyone has reasons to explain that I am wrong in my above
understanding of the importance of the host's CPU speed, please
explain. My experience with multiple CPUs and multiple core CPUs is
quite limited, however my experience with CPUs of various speeds in
virtualisation hosts indicates to me there is at least some truth to
my statement. It is great to be able to ask this question of others
who have more experience and access to a wider range of equipment.


Thanks for your comments. I am pleased to learn that Ansible is truly
Open Source (er, not proprietary).  I hope you will be able to speak
at CLUG on this topic.

I am interested in the TrippleO Ansible installation of OpenStack as I
believe it will provide a more "real world" test environment (and be
easy to install). (I think I may have made this comment before, and it
still what I am expecting until proven otherwise).

I prefer to model my test environments as close as possible to the
real world, production environment. The main difference being load,
but as test environments are usually run on less than idea hardware
(i.e. less performance/power), this can partly compensate for the lack
of real world, work loads.


Apologies to you if hypervisors are of little interest to you.  I
will say that I find them great for running my home web services, my
local file server, and for running personal/home games servers (Ark
Survival Evolved and various modded Minecraft servers).  I am
guessing you don't have much use for or interest in running any of
these types of servers?   And I understand that there are many
really great NAS systems that offer cloud access, and require little
effort to set up (_but can they run a Minecraft server ! ? !  alas, I

To ask, do you have any Linux topics that you would like to see people
give talks on at CLUG?  I am always keen to explore Desktop GUIs
further. I learned much from others sharing their experiences.  I am
currently enjoying Debian with Cinnamon's Jet-Gray and Windows-7-Aero
themes as my primary computer. Previously I was using Xfce, and in the
future I hope to try other GUIs and themes. I like how Linux provides
people with such a wide variety of choice, different to the famous
statement "Any customer can have a car painted any colour that he
wants so long as it is black".

General comment,

At home I am currently using Virt-Manager and KVM for my hypervisor

I have one Desktop, one laptop running both Virt-Manager and KVM on
Debian, and one CentOS 7 KVM (close to bare metal) hypervisor.
Virt-Manager on the laptop or desktop can manage any of the desktop,
laptop, or CentOS 7 KVM hypervisors.  

My aim is to add a second CentOS 7 KVM hypervisor at a later date
(time permitting). I find that Virt-Manager and KVM provides an
effective hypervisor sytem, and I like how Virt-Manager can display
the performance of the KVM Host, and Guest virtual servers. I have
found moving the Guests from one server to another problematic as
Debian's guest configs are different to CentOS guest configs. Is there
some script that can easily convert between these differences ? I do
not know of any, but then I have not looked for one either.


I have yet to work with containers, but acknowledge their usefulness
even if I have yet to experience working with them.  I did notice
when I installed DevStack, that its installation of OpenStack provides
a way to manage containers.


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