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Maximum tolerable period of disruption: a new definition

Mel Gosling argues that the current definition of the term maximum tolerable period of disruption (MTPD) not only causes confusion, but is actually wrong, and needs to be replaced by a definition that will ensure that the concept is both readily understood and used as originally intended.

The maximum tolerable period of disruption (MTPD) is the term used for the requirement within which a recovery time objective (RTO) needs to be set. It has been around for some years now, but as recent research undertaken by Continuity Central shows, it is not universally accepted by business continuity practitioners and still seems to cause a great deal of confusion. In my opinion, this lack of acceptance and confusion has been created by its definition.

The BCI's Good Practice Guidelines (GPG) defines MTPD as “The duration after which an organization's viability will be irreparably damaged if a product or service delivery cannot be resumed.” This seems straightforward and unambiguous enough, but it's only when you look closely at the definition and try to think about how it might be applied in practice that you'll see that not only is it of very little use, but it is also different from what was originally intended.

If something doesn’t work in practice then the theory is wrong. The idea that there is some point beyond which an organization's viability will be irreparably damaged if a product or service delivery cannot be resumed would be an extremely useful concept if such a thing existed. However, in practice, you will never really know if an organization's viability has been irreparably damaged until the organization fails, let along the point at which this happens.

It's only after there has been an incident that has caused disruption to the delivery of a product or service that you might be able to see if the organization's viability has been irreparably damaged, and even then it won't become apparent until a long time after the disruption. In fact, there won’t be an identifiable point in time after which the organization's viability has been irreparably damaged; it will just be understood to have become an irreversible fact. The actual point at which the non delivery of the product or service caused the irreparable damage will not be known, even after it’s realised that the damage is irreparable. If this is the case, how can you possibly identify that point in time before an incident has occurred?

This though, is exactly what business continuity practitioners are doing today when they try to use the current definition of MTPD when undertaking a business impact analysis (BIA). It should come as no surprise, therefore, that they find it difficult to identify the MTPDs of an organization's products and services, let alone the MTPD's of the activities that need to be undertaken to ensure their delivery.

The concept of the MTPD is a necessary pre-requisite to determining recovery strategies as it sets the boundary within which the RTO needs to be determined. It makes sense, therefore, to try and identify a definition that works in practice (after all, this is how science works – observe what happens in practice and formulate the theory around the observations).

In practice, it's much better to think about the time after which the impact of the disruption on the organization becomes too great to be accepted, as it's something that people can stand a chance of estimating. So, instead of asking "At what point would the non delivery of product X cause your organization to be irreparably damaged?" I ask "At what point would the impact on your organization caused by the non delivery of product X become too great?"

The difference between these two questions is not minor as they are asking two very different things. The first question, which uses the current definition of MTPD, is trying to obtain the answer “Our organization would be irreparably damaged if we failed to deliver product X after Y hours”, whereas the second question is trying to obtain the answer “The impact on our organization would be unacceptable if we failed to deliver product X after Y hours.”

The BCI's definition of MTPD assumes that there is a point after which there is irreparable damage, and before that point there isn't irreparable damage. In reality, things aren't so black and white. The longer the disruption goes on and the greater the impact, the more likely it is that the viability of the organization will be threatened, and the more unacceptable the disruption becomes. There is no single point after which there is irreparable damage; instead there is an impact curve, and at some point on that curve the impact becomes unacceptably large.

For many organizations, and for many products and services, the impact curve would be S shaped, as shown in the figure one below.

MTPD fig one

[Click the image for a larger version]

This shows that the impact from a disruption can be relatively small for a period of time just after the incident, rising rapidly as time moves on towards the situation where there is irreparable damage. At some point on that curve, the impact becomes unacceptably large.

For other organizations, particularly those that have penalty clauses in place for the non delivery of a product or service, the impact curve would not be smooth.

The MTPD is estimated as the point at which the impact on the organization is deemed to be unacceptably large, as shown below in figure two.

MTPD fig two

[Click the image for a larger version]

This is how people perceive the MTPD. They don’t know the point at which their organization would be irreparably damaged, but they do know when the impact on the organization becomes too great.

Summary

The MTPD is a necessary concept, but it needs to be readily understood if it is to be used as the requirement against which the RTO can be determined. The current definition is incorrect and needs to be changed.

As a start, I suggest that the definition of the MTPD becomes “The duration after which the impact on an organization caused by the non delivery of a product or service becomes unacceptably large.”

The author

Mel Gosling

Mel Gosling is a Member of the BCI, and is managing director and the principal business continuity consultant of Merrycon Ltd. He can be contacted at melgosling@merrycon.com, and has recently started to write a Business Continuity Consultant’s blog, which can be found at http://www.merrycon.com/blog.html

Make a comment

There have been many reader comments about this article. Read them here.

•Date: 7th Jan 2011 • Region: UK/World •Type: Article •Topic: BC general

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