When investigating the purchase of computer servers it is important to understand the terms “Mean Time Between Failure” (MTBF) and “Mean Time to Repair” (MTTR). Here is a link to an outstanding article by George Spafford that expains the terms and gives good examples of each.
Understanding ‘Mean Time Between Failure’
May 14, 2004 by George Spafford in Datamation
http://itmanagement.earthweb.com/columns/article.php/3354191