A company whose IT services are being delivered from a Tier 4 data center should be most concerned with application failures when preparing a companywide BCP. A BCP is a document that describes how an organization will continue its critical business functions in the event of a disruption or disaster. A BCP should include a risk assessment, a business impact analysis, a recovery strategy, and a testing and maintenance plan.

A Tier 4 data center is the highest level of data center classification, according to the Uptime Institute. A Tier 4 data center has the highest level of availability, reliability, and fault tolerance, as it has multiple and independent paths for power and cooling, and redundant and backup components for all systems. A Tier 4 data center has an uptime rating of 99.995%, which means it can only experience 0.4 hours of downtime per year. Therefore, the likelihood of a power, storage, or network failure in a Tier 4 data center is very low, and the impact of such a failure would be minimal, as the data center can quickly switch to alternative sources or routes.

However, a Tier 4 data center cannot prevent or mitigate application failures, which are caused by software bugs, configuration errors, or malicious attacks. Application failures can affect the functionality, performance, or security of the IT services, and cause data loss, corruption, or breach. Therefore, the IT manager should be most concerned with application failures when preparing a BCP, and ensure that the applications are properly designed, tested, updated, and monitored.