How to determine fault tolerance...

Posted on 2006-03-22
Last Modified: 2008-01-09
Hi Experts,

Is there a process to determine the level of fault tolerance needed for a particular business operational function?

Question by:hermor
    LVL 11

    Expert Comment

    Depends on the operational function.. what is it?
    LVL 3

    Assisted Solution

    you can try this, im not sure if it helpful.
    it also hase number of references.

    also this
    LVL 57

    Expert Comment

    The level of fault tolerance needed for for a business function is based on the users requirments that need that business function.
    LVL 7

    Accepted Solution

    You need to ask some questions such as:

    What is the required recovery time in the event of failure.  All business users will say they need 100% availability, it is always the goal.  But, if the system was down, how long could it be down without a real impact to the business.  This tends to guide the tolerance level built.  Generally speaking you can either use mirroring or raid V.  

    Mirroring gives you tolerance for disk failure.  In the event of a disk failure, usually on reboot the raid controller acknowledges that the drive has failed and boots off the mirror.  Then you can replace the original drive during off hours and rebuild the mirror.  So in this case the recovery is almost instantaneous, usually a few (5-10) minutes.

    Raid 5 uses parity and spreads the data accross multiple drives.  Usually you have a hot spare (a drive just sitting there waiting).  Upon failure, the controller will rebuild the bad drive on the hot spare based on the info on the other drives in the array.  Depending on the size of the drives, how much data needs to be rebuilt, and the power of the server, this can take 10 minutes to a few hours to rebuild.

    This will also depend on the size of the array you are building.  There are quite a few variables involved in making this decision, so be sure to understand the business need and size the server appropriately.  In general, it is easier to expand a raid 5 array than a mirrored one.

    Here's a helpful article:


    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    IT, Stop Being Called Into Every Meeting

    Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

    Suggested Solutions

    Title # Comments Views Activity
    Binomial distribution 2 41
    A PDF to HTML file converter 2 69
    Isolating a VM 1 51
    Car Question: Honda CRV 2005 Knock Sensor 3 0
    Finding a job can be stressful - searches, resume tweaks, and networking events can be super boring. Luckily we're here to help you land your dream job!
    Whether you're new to the game or an experienced player, you can never get enough help trying to have the best Pokémon. This guide will do its best to serve and be a living document.  It will evolve as I have more things to add or change.
    Video by: Kyle
    After watching the Introduction to GIMP and additional tools to use in GIMP we are shown how to utilize multiple tools to create a 3D effect image.
    Where to go on the main page to find the job listings. How to apply to a job that you are interested in from the list that is featured on our Careers page.

    761 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    8 Experts available now in Live!

    Get 1:1 Help Now