Most data centers employ either CCTV, audio surveillance systems, or a combination of the two. These systems typically feed into a guard station, where they are monitored by security personnel and recorded on either tape or a digital storage system.
Surveillance cameras are a detective control as well as a deterrent for would-be thieves. The absence of surveillance systems would increase the risk of theft and other criminal activities.
When auditing a data center, the auditor should review camera quality and placement as well as tape rotation or mass-storage archival schedules. This can be done through a combination of document review and observation. The data center security manager should be able to provide this information.