Monday, 28 January 2013

How many administrators do you need for your operations?

How many administrators do you need for your operations?

Several online resources are discussing this issue. it usually depends on several factors such as :

I- Factors that could reduce the number of admins needed:
  • Remote console/power and remote management tool availability
  • Vitalisation
  • Physical server, and rack technology (e.g. blades or skinless vs. U2 servers)
  • Availability of management tools  (rack management, api such as in EC2, and cloud providers)
  • Platform ( e.g. Unix, and Unix like vs. Windows )
  • Configuration management and automation tools.
  • Initial plan, and vision of business/data centre expansion
  • Organisation requirements, maturity, stability, and adoption of the devops culture.
II- Factors that could increase the number of admins needed
  • Size and diversity of data managed.
  • Number, and diversity of servers and server configurations
  • Number of users
  • Number and diversity of applications used and  supported*. 
  • Number of new technologies at the ground or acquired within  the data centre
  • Complexity of the solution and infrastructure.
* used by the administration  team, and supported on behalf of others within or external to the organisation.
So what is the best practice metric that should be used? it depends on what kind of operations the business is running and how messy, or diverse it is customer or application space, as well as management approach towards operations and support from the start. not to mention what we mean by best practise is the best try, best deployment plan, however as soon as it materialised it can be improved so it becomes good practise or  could be even bad if it did not evolve

CERN did not use virtualization to help deploy and run  their HPC codes, however have chosen to adopt virtualization to ease out administration and management costs

FaceBook  230 engineers supporting data for over than more three million users, at around 130 servers per admin  [1]

Microsoft automated data center operations at around 1000-2000 servers per admin, while its new container data center will be around 10,000 server/DC employee.

IDC reports in large dominant  providers such as Google, it could be 10,000 servers/admin while in small to medium businesses it could be 30:1 for physical boxes and 80:1 for virtual machines. [2]

Gartner analyst, Errol Rasit says “We have observed that it can be, for example with a physical server, as low as 10 per admin, and for virtual servers as many as 500,”

resources :

[1] Data Center Knowledge Article "how many servers can one admin-manage"

[2] Computer World Australia IDC reference 

Wednesday, 23 January 2013

CFEngine3 by examples

CFEngine3 by examples : CFEngine3 3.4.x is the latest community release from CFEngine, one of the new features that was missing is the publicly available reusable easy to do/read policies. in the terminology of CFEngine i believe it is called sketches,  they are another form of describing your system desired end state using promises, however in this case you are getting them, or publishing them in Design-Center.  Nick Anderson a Motorola employee and an experienced long term CFengine and advocator have released publicly an easy to develop and test environment using vagrant in Github.  along with examples to get one started quickly. ignoring the download times of Vagrant, Git, and CFengine codes, the process should not take you more than 5-10 minutes. I have realized that CFEngine do not release binaries for OSX, so i used brew to get the latest CFEngine which was 3.4.1, while the latest at this time was 3.4.2. not bad! ha!. i had to download also the xcode command line tools to get make, gcc among other development tools to get things build and working.  No excuse on getting more familiar with CFengine in no time, especially that CFEngine senior security adviser and Orielly book "Learning CFengine 3" author sent me a chapter from his 3rd edition regarding vagrant and Behavioral testing for CFengine.