Managing performance: What you don't know will hurt you. By Denise Dubie

The old saying "ignorance is bliss" doesn't apply to the myriad factors that can contribute to poor application and network performance. The less network managers know about the components in their environment that impact performance, the more likely they suffer unplanned outages, application performance degradation and costly network downtime. The problem is rooted in a lack of visibility into network and application performance, according to industry watchers.

http://www.networkworld.com/newsletters/nsm/2008/120108nsm1.html