Eye on Hosted Video: How to Keep Recording if the Network Fails

Maintain critical surveillance coverage with NAS and SD memory cards


Network failures are pretty uncommon these days, thanks to ISP innovations, network technical service and redundancy plans. Yet there can still be times when your network might be unavailable, like if a local switch or router crashes or someone accidentally unplugs a cable. And even in a hosted video application, video management systems (VMS) might be taken offline periodically for server upgrades and scheduled maintenance. This has led to a popular hosted video myth: If my network goes down, I lose my surveillance capabilities.

To avoid losing critical surveillance coverage during potential outage intervals, consider installing an onsite backup system to cache the video locally.

But wait a minute — isn’t one main selling point of a hosted video system that you don’t need onsite storage? Aren’t we getting rid of the DVR with hosted video? Yes, hosted video does replace the need for expensive, high-maintenance DVRs for onsite storage; however, if you cannot afford even a brief lapse in your hosted recording, there are two common off-the-shelf and inexpensive local storage options: Network Attached Storage (NAS) drives and SD memory cards.

NAS: Backup and Recovery on Demand

The NAS device installs on the same local area network (LAN) as the network cameras. The cameras can be programmed to stream video to the cloud and the NAS simultaneously 24/7, or just to the NAS if the connection to the cloud is lost. Once the connection is re-established, the NAS can upload its stored video to the cloud automatically, or be offloaded on either a scheduled or manual process, depending on how you have programmed your surveillance system.

Since the NAS is attached to the LAN, you can also view NAS-stored video from any desktop, laptop or mobile device that has access to the network. It is transparent to the user whether the video came from the NAS or the cloud.

A NAS device is easy to install because it can be registered to the hosted video service portal with a single click. It is also a cost-effective backup solution since multiple cameras can share the same storage device. The NAS can be programmed to record multiple streams at different frame rates and resolutions, giving end-users both a redundant safety net for storage and the freedom to configure the cameras in the system for various performance levels and image quality (including HDTV and megapixel) depending on a particular application and its security needs.

A high-quality NAS unit typically costs around $250 for two terabytes of storage, which is more than enough for up to 10 cameras to share.

SD/SDHC/SDXC Cards: An Alternate Video Backup Plan

Another backup option is the SD memory card. An SD (secure digital) memory card — whether SD, SDHC or SDXC format — is the same type of card found in digital photography cameras and Smartphones to store pictures, music and video. This solution is commonly referred to as “edge storage” because video storage happens inside the camera — at the edge of the system. The standards for memory card storage are set in the consumer electronics industry by the SD Association.
SD cards are a great solution for sites with one or only a few cameras. But the cost per gigabyte of storage is higher than with an NAS device.

There are two basic ways to use SD cards for video back up. One is to program the camera for continuous recording to the SD card regardless of whether the hosted video application is accessing it or not. In this scenario, the VMS must identify that it has a gap in its video reception and request the missing clip from the camera so that it can be merged into the recording database.

The other way is to instruct the camera to buffer video on the memory card whenever a communication session with the cloud is abruptly terminated instead of properly closed. Once communication is restored, the hosted video application in the cloud can retrieve the missing video, restore fail-over recording and delete the video on the SD card. If the hosted video system does not offload the SD card before it reaches full capacity, the camera will simply stop recording to the memory card.

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