simply speaking, a cloud consists similar computers (homogeneous hardware). usually every single cloud computer runs the same OS (host system), each controlling various guests. the main technical motivations are:
- load balancing of cpu load (move the VM to a machine with more CPU power)
- load balancing of input/ouput load (RAM increase; faster storage raid; in memory databases)
- load balancing of bandwidth usage (move the VM to the most demanding users)
- increase redundancy (reduce hardware failures; reduce power loss issues)
- marketing – ‘cloud’ sounds cool, although a ‘cloud’ is basically just a subset of the internet
- vendor lock-in – probably no surprise to anyone
- centralization – cheaper to manage; grants more control over the platform
if you are a customer to a service which is hosted in the cloud you usually don’t see the cloud at all, hence the term ‘cloud’:
- amazon: when buying books or other things
- google: using google search; reading email; google maps
- microsoft azure: whatever that platform is good for, is actually anybody using this?
- actively maintain each computer: implement distributed file systems and distributed services
- using an abstraction: someone implemented the handling of nodes and services you are going to develop thus it is running on top of an abstraction
- SaaS – Software as a Service (something like google mail)
- PaaS – Platform as a Service (something like ms azure / amazon e2)
not too long ago you would have maintained your own infrastructure with access to the hardware and software used. but times have changed and the americanization of things, that is by building ‘super services’, is about to change the internet yet again.
i see this issues (no special order):
loss of control
this is probably the strongest argument against using third party proprietary services as you can’t fix it when it is broken. but cloud computing usually means a loss of privacy as well. the article  mentioning various points from richard stallman and larry ellison probably makes this point clear. it is interesting to see this SaaS wikipedia article  which reads like a campaign for SaaS – probably written by someone with a marketing background. there is the dangers to loose your data to foreign countries, as mentioned in .
loss of own infrastructure
you don’t have your own infrastructure anymore, thus you don’t have physical control over your devices. additionally you then depend on working internet connections. it is likely that the infrastructure you rely on runs in one or several different countries.
loss of software not designed for the cloud
the various versions of the GPL had a great influence on how software could be used and distributed but with the advent of the cloud this changes drastically. the way programs, especially webservices, are designed makes the GPL concept useless as it does not affect you at all. however, there is a new license, the ‘Affero General Public License’  which fills that gap.
why is wordpress is not licensed AGPL i wonder? my first guess is laziness as every author of every single patch would have to be asked for license change persmission. but the wordpress hosters could be using the GPL to greenwash their software as they would not have to hand out proprietary extension which might not be released. but who knows?!
loss of knowledge how to setup services similar to today’s cloud servcies
think about email – who operates his own mailserver nowadays? most friends of mine use google mail and this implies: once you are familiar with a service and its workflow you usually do not want to change. especially if the service seems to be free as in google mail for example (but most of my friends seem not to care that google replaced ‘currency’ by ‘privacy’ which is used as payment instead).
as a consequence the knowledge about how to run your own mail server gets lost. if you understand german, listen to alternativlos 18 – ‘Peak Oil, den Weltuntergang, und wie man sich vorbereiten kann’  minute 74 ff – they discuss this issue.
my personal experience
i have a strong tendency to use devices which are capable of bringing me certain services offline. this is why i put a lot of effort into the evopedia application for instance. the nokia n900 is probably another good example where i try to maintain an offline infrastructure – i didn’t even have mobile internet on the n900 for a complete year and yet i was able to do most things using sip/mappero/evopedia and others.
here are some thoughts about online services i use:
i use wordpress.com right now and i really hate it for these points:
- you can’t write offline
- initial uploading images or updating them is a frustrating process
- i sometimes loose parts of articles while writing
- there is no good backup process for offline backups
- i hate the WYSIWYG editor as it does not work very well
- wordpress is inconsitent in producing a good web 2.0 workflow, it feels like reloading the page all the time instead of doing so for single dom-tree elements only, as it would be done with web 2.0; if you don’t trust me, have a look at  – how the upcoming wikipedia editor works
i really love ‘google docs’ as it is a wonderful collaborative platform but i can’t use it as i have to disclose all documents to google i’d be working on.
like google mail and google docs, android has a very good cloud integration. but if you want to use services other than google’s, it is a horrible platform. for instance i keep installing xabber  although google uses jabber but intentionally made you require to install third party software in order to use non google jabber. same goes for most other services. if i had to use an android phone i would buy one with proper CyanogenMod  support.
great service for source code hosting using git. still the platform itself is not available like for http://gitorious.org/ or http://gitlabhq.com/. github.com uses a wiki which is bound to the platform and not contained in the git repo.
note: although i never used http://www.fossil-scm.org i like the idea that it contains a wiki in the repository as well
i use github.com only for free and open source projects.
better without clouds
the conventional use of the term ‘cloud’ simply indicates a buzzword or business term for vendor lock-in and centralized infrastructure you don’t have control of. that is good to know as it helps to recognize and avoid such services. what one should use instead is decentralized infrastructure located near the user, connected to the internet where needed, giving the user the control over the platform.
arguably this concept is implemented as a new trend called ‘personal cloud‘ or ‘private cloud server‘. but these terms are limiting the trend to personal or private matters, yet i would like to see it in businesses as well.
following the concept of decentralization users can host their own files and other things as address books / calenders on their own home devices.
a list of interesting devices to give you an idea:
- sheevaplug  – there is even a nixos version for this device (by viric)!
- pogoplug 
- tonidoplug 
- fritz!box (with myfritz and fritznas) 
software implementing services
a list of software i find interesting:
- despora  – decentralized facebook
- owncloud  – dropbox like service
- sparkleshare  – is a collaboration and sharing tool that is designed to keep things simple and to stay out of your way.
- tomahawk  – a nice music streaming service
- various p2p / torrent like services:
- mldonkey 
still most ‘personal or private clouds’ scale differently compared to the big 3 mentioned in the beginning of this article. for instance, most of these services are configured in the client/server way and they usually do not implement concepts as failover, backups or load balancing. for that to happen it requires a new set of tools and decentralized frameworks based on p2p technologies – which has just not happened yet.
there is also a political issue: most internet users do not have a decent upload channel, which basically means that their internet connection is not very good.
software for managing services
- openshift  – is a cloud computing platform as a service product from red hat
- openstack  – is a global collaboration of developers and cloud computing technologists producing the ubiquitous open source cloud computing platform for public and private clouds.
- disnix  – is a distributed deployment extension for Nix, a purely functional package manager.
a matter of design
to make the private cloud or a decentralized cloud a success we need:
- a standardized package manager with proper software life-cycle management
- symmetrical internet connections with decent upload/download speeds
- transparent support for scalability/reliability/redundancy (the points mentioned in the beginning of the article)
- powerful hardware with low power usage but capable of high loads
- encryption and certificates or a chain of trust
- ipv6 – we need good endpoint communication capabilities
- a clear understanding of where we want to put our personal data and how we can protect it
still it is a long way for the private clouds to have the same level of features/quality as the big clouds already have. for the time being it seems to be complicated for the average internet user to use the internet without loosing too much of his individuality, thus the freedom of expression.