According to recent surveys, at least 80% of the CCTV systems are installed with the main purpose of recording footage for inspection in case of incident. Probably there is nothing more frustrating than figuring out right during the investigation, that the system failed to record the picture or the clip that could have been used as evidence to prosecute a crime. This article has the purpose to shed some lights on the different recording methods offered by MOBOTIX systems and outline some best practices to achieve reliable recordings.
The camera is just one element of the ecosystem. Other elements could be a NAS, the Hard disk drive, the network as such, flash devices and the power supply. All of these elements have to be planned and configured in detail to achieve a reliable running system.
Regarding storage, firstly the right storage media has to be chosen. Should the recordings be saved on a NAS drive, a SD card or even both? MOBOTIX cameras offer the possibility to record on any of these medias without need for additional software or computer connected to the network.
To be considered is the bandwidth for example with a very low bandwidth it is recommended to store on the SD card in the camera. However, if a flash device is chosen as a storage, a special attention should be paid to the quality of the media itself. Oftentimes cheap devices turn out to be more expensive because they tend to fail more often and, more importantly, they may prevent you from retrieving important footage. An in-depth tutorial will follow on this topic.
Also the redundancy is a criterion, should there be a backup storage of recordings? The new MxFFS Archive Storage allows you to use a NAS as target device and a flash card as a failover. This means that when the NAS is not available the camera will keep recording on the flash device (i.e. microSD card) but as soon as the NAS is reachable again, the camera will transfer to it all the recordings stored into the flash device. If you want to know more about this follow this link.
The storage capacity can be influenced by several factors such as image settings, frame rate, recording mode and retention time. The MOBOTIX storage planner tool is available on our website www.mobotix.com under the Partner Section (Login required).
Chosing the NAS
When choosing a NAS important characteristics is the CPU, RAM and the capacity. As a general recommondation 20% of the disk should stay unoccupied. This because it’s proven that the performance of the NAS are drastically reduced when the hard drives are full.
Further properties are the number of bays, the RAID level, an automatic restore after power failure and a redundant power supply. All of these traits are essential for choosing a NAS. Also the Hard Drives should be chosen carefully: read/write speed is important but for CCTV the main factor is the resiliency, in other words the ability to work in non-ideal conditions (vibrations, high workload, high temperature) and over long periods of time (24/7 - 365 days a year). There are specific HDD designed for this kind of applications.
Once the NAS has been chosen it should feature an up to date firmware, an NTP server for all network devices to have a synchronized time stamp. Time synchronization is not only necessary to be able to search and playback recordings, but also to ensure the consistency of the data written within the camera database. If the system devices cannot reach a public NTP server, you can consider the addition of a GPS-Box to your installation. Moreover, if several cameras shall record to the same NAS, its multiple Ethernet interfaces should be bundled to increase the bandwidth. Of course this option is not available on all the devices, so please ask your supplier if you are not sure.
Further the recycle bin should be turned off: this option is available for the vast majority of the NAS devices. It’s very useful if you want to be able to restore the holiday’s pictures that you have accidentally deleted but it’s deadly for a CCTV system with continuous recordings. In fact the NAS needs to process many more files when the cameras ask it to override old recordings and this heavily impacts on the overall writing performance. The opportunistic lock should be disabled too and on the other hand diagnostic tools and error notifications should be enabled to be informed at a very early stage if something is not working properly. Believe me, this will avoid you a lot of headache.
On the side of the camera the following settings and properties should be considered. The firmware has to be up to date and the same NTP server as mentioned earlier has to be set. Also keep the archive size and time to keep, the image size, and the frame rate in mind.
When you install a CCTV system you should always keep into consideration the local regulation in terms of data protection. Such a regulation may limit the retention time from 24 hours up to 30 days. Either way, MOBOTIX cameras give you all the tools to be compliant with the data protection regulation; in fact they can be configured to override older recordings when the retention time is reached. MOBOTIX also supports intelligent recording, which means that you can record only upon event to save storage space or, if you want to make sure not to miss a thing, you can record continuously at a given frame rate and at a higher frame rate in case of event.
Other important factors with impact on the storage capacity is if it is event or continuous recording, the recording time and the event dead time respectively the re-trigger of a sensor. The reason being that to make a better use of the resources of the NAS we should avoid fragmenting events in unnecessary sub-events.
The camera can provide error notifications so these should be enabled to ensure a working system failure management. Error notifications can consists of e-mail, VoIP calls, IP Notifications, alarm sounds and much more.
The next element in the ecosystem is the network as such. Can the network be physically separated or can Virtual LANs be created? Generally it has to be able to handle the network load created by the cameras, the PC and the NAS. The minimum bandwidth requirement of all devices has to be known to set it up in a proper way. For sure the capacity of the switches, quality of servers and the possibility of traffic prioritization play an important role in this context.
Make sure the latency periods are less than 5 ms and look for collisions and package losses on the network. Although wireless technology represents a very tempting alternative to the classic CAT cable (due to the fact that it’s fairly cheap and easy to deploy), we strongly recommend against if you intend to use it in CCTV applications. The reason being that WiFi is not as reliable as Ethernet (packets can be lost due to interference, disconnections, etc…) and it’s also more prone to be target of cyber attacks.
Last but not least we need automatic error notifications for predictive maintenance. During the planning phase it has to be clear who should be notified when something goes wrong. After the installation is completed and the system is up and running, keep an eye on the performance of the NAS and schedule periodic checks to make sure that everything runs as expected. The first check could be done after a week, another one after a month and the last one after 3 months. This will give you the possibility to spot issues and avoid the typical frustration generated by lack of important recordings.