Human factors in availability of systems

Usually only 20% of the causes of failures are technology failures. In 80% of the cases, human errors are the reason. For instance, a system administrator accidentally pulls a wrong cable or enters an incorrect command. Users sometimes delete inportant (system) files.

Of course it helps to have highly qualified and trained personnel, with a healthy sense of responsibility. Errors are human, however, and there is not a cure for it. End users can introduce downtime by misuse of the system. When a user for instance starts the generation of 10 very large reports at the same time, the performance of the system could suffer in such a degree that in fact the system is unavailable to other users.

Also when a user forgets a password (and maybe tries an incorrect password for more than 5 times) he is locked out and the system is unavailable for him. If that person has a very reponsible job, for instance approving some steps in a business process, being locked-out could mean that a business process is unavailable to other users as well.

Most unavailability issues however are the result of actions from system managers. Some typical actions (or the lack thereof) are:

  • Performing a test in the production environment (hopefully by accident - testing in production is of course not recommended at all)
  • Switching off a wrong component (not the defective server that needs repair, but the one still operating)
  • Swapping a good working disk in a RAID set instead of the defective one
  • Restoring the wrong back-up tape to production • Accidentally removing files (mail folders, configuration files, database files)
  • Incorrect changes to configuration files (for instance the routing table of a network router, or a change in the Windows registry)
  • Tripping over cables, creating a broken or disconnected cable • Incorrect labling of cables, later leading to errors when a change is performed
  • Stopping an incorrect virtual machine (the one in production instead of the one in the test environment)
  • Making a typo in a system command (in UNIX: sudo rm -rf / *.back instead of sudo rm -rf /*.back where one space too many leads to a complete erasure of a hard disk - did you notice the difference?)
  • Insufficient testing, for instance the fall-back procedure to mover operations from the primary datacenter to the secondary was never tested, and failed when it was most needed
  • A system manager or architect made a mistake in the design of the infrastructure, leading to downtime (we thought the Windows cluster was designed in a good way, but when one of the cluster nodes failed, we found that the complete cluster went down)

Many of these mistakes can be avoided by using proper system menegement procedures, like have having a standard template for creating new servers, using formal deployment strategies with the appropriate tools, using adminstrative accounts only when absolutely needed, etc.

When in some UNIX environments the user works under a administrative account (root), automatically he gets the following message:

We assume you have received the usual lecture from the local System Administrator. 
It usually boils down to these three things: 
#1) Respect the privacy of others. 
#2) Think before you type. 
#3) With great power comes great responsibility. 

I think this message makes people aware, leading to fewer mistakes.

This entry was posted on Tuesday 28 June 2011

Earlier articles

Infrastructure as code

My Book

DevOps for infrastructure

Infrastructure as a Service (IaaS)

(Hyper) Converged Infrastructure

Object storage

Software Defined Networking (SDN) and Network Function Virtualization (NFV)

Software Defined Storage (SDS)

What's the point of using Docker containers?

Identity and Access Management

Using user profiles to determine infrastructure load

Public wireless networks

Supercomputer architecture

Desktop virtualization

Stakeholder management

x86 platform architecture

Midrange systems architecture

Mainframe Architecture

Software Defined Data Center - SDDC

The Virtualization Model

What are concurrent users?

Performance and availability monitoring in levels

UX/UI has no business rules

Technical debt: a time related issue

Solution shaping workshops

Architecture life cycle

Project managers and architects

Using ArchiMate for describing infrastructures

Kruchten’s 4+1 views for solution architecture

The SEI stack of solution architecture frameworks

TOGAF and infrastructure architecture

The Zachman framework

An introduction to architecture frameworks

How to handle a Distributed Denial of Service (DDoS) attack

Architecture Principles

Views and viewpoints explained

Stakeholders and their concerns

Skills of a solution architect architect

Solution architects versus enterprise architects

Definition of IT Architecture

What is Big Data?

How to make your IT "Greener"

What is Cloud computing and IaaS?

Purchasing of IT infrastructure technologies and services

IDS/IPS systems

IP Protocol (IPv4) classes and subnets

Infrastructure Architecture - Course materials

Introduction to Bring Your Own Device (BYOD)

IT Infrastructure Architecture model

Fire prevention in the datacenter

Where to build your datacenter

Availability - Fall-back, hot site, warm site

Reliabilty of infrastructure components

Human factors in availability of systems

Business Continuity Management (BCM) and Disaster Recovery Plan (DRP)

Performance - Design for use

Performance concepts - Load balancing

Performance concepts - Scaling

Performance concept - Caching

Perceived performance

Ethical hacking

Computer crime

Introduction to Cryptography

Introduction to Risk management

The history of UNIX and Linux

The history of Microsoft Windows

The history of Novell NetWare

The history of operating systems - MS-DOS

The history of Storage

The history of Networking

The first computers

History of servers

Tips for getting your ITAC certificate

Studying TOGAF

Is your data safe in the cloud?

Proof of concept

Who needs a consistent backup?

Measuring Enterprise Architecture Maturity

Human factors in security

Master Certified IT Architect

ITAC certification

Open group ITAC /Open CA Certification

Human factors in security

Google outage

SAS 70

TOGAF 9 - What's new?

DYA: Development without architecture

Spam is big business

Why IT projects fail

Power and cooling

Let system administrators participate in projects

The 7 Habits of Highly Effective People


A meeting with John Zachman

ITAC - IT Architect certification

Personal Information is Personal Property

The Irresistible Forces Meet the Movable Objects

Hardeningscheck and hack testing for new servers

Knowledge management

Information Lifecycle Management - What is ILM

LEAP: The Redmond trip

LEAP: The last Dutch masterclasses

What do system administrators do?

Is software ever finished?

SCADA systems

LEAP - Halfway through the Dutch masterclasses

Securing data: The Castle versus the Tank

Non-functional requirements

LEAP - Microsoft Lead Enterprise Architect Program

Reasons for making backups

Log analysis - Use your logging information

Archivering data - more than backup

Patterns in IT architecture

Layers in IT security

High performance clusters and grids

Zachman architecture model

High Availability clusters

Monitoring by system administrators

What is VMS?

IT Architecture certifications

Storage Area Networks (SAN)

Documentation for system administrators


Presentations: PowerPoint sheets are not enough

99,999% availability

Linux certification: RHCE and LPI

IT Infrastructure model

Sjaak Laan

Recommended links

Ruth Malan
Gaudi site
Esther Barthel's site on virtualization
Eltjo Poort's site on architecture


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