IP-surveillance systems are surveillance systems designed to send video and audio over IP-networks, to be able to function a typical system consist of IP-cameras to record footage, a client to view footage and recordings, network hardware to send the data, protocols to administer storage and viewing operations and last but not least a location to store the captured data. One of the options for storing surveillance video is to use a Network Attached Storage. Axis has received customer cases reporting lost footage and cameras losing their connection when using NAS-devices as storage in IP-surveillance systems. This thesis aims to investigate what a NAS is and how it interacts with cameras in an IP-surveillance environment by analyzing the protocols and components being used and by performing experiments to locate the system bottleneck causing these problems. After concluding that the hard disk drive was the bottleneck because of the overload imposed on the other components by the incoming data traffic and how data is moved and temporarily stored in a system. Recommendations of possible ways to remedy these problems were suggested with the proposed problem of solving the bottleneck problem was to add more disks to improve performance, this was the second aim of the thesis, which sadly was not possible because of the 2-bay NAS systems being used in the tests. The third and final aim was to establish and develop method guidelines for testing NAS-systems. This was done by using previous research in the area and using data encountered when trying to locate the bottleneck.