VMS Redundancy Through SD CardsBy: John Honovich, Published on Nov 18, 2009
March Network's enhanced storage management features includes a means to provide simple and inexpensive VMS redundancy. View the announcement for an overview and a whitepaper for details [link no longer available] (registration required).
Video can be simultaneously recorded on March's IP cameras using SD cards and March's VMS system. If the VMS goes off-line or network connection is lost, the IP cameras can continue to record.
The March network viewing client can continue to display live video from the cameras by directly connecting to the cameras. Additionally, when connectivity to the VMS is restored, the VMS can automatically re-synchronize video from the SD card that was not originally captured on the VMS.
There is no additional software to add or licenses to buy. The cost is simply the price of the SD card. SD card size can be selected to provide protection for given period of projected outage (e.g., if you want to make sure that video continues to record even in the event of a 3 day outage, select an SD card size that will provide 3 days or storage for the video quality settings used for that camera).
This approach is not only inexpensive but makes it flexibile to enable just the cameras that one most values redundancy.
A number of alternative techniques are available though the traditional ones tend to be expensive and technically complex including manufacturer proprietary solutions at the application layer, at the OS and more recently using virtualization (see Pivot3's feature as an example). Avigilon recently added a simple and inexpensive redundancy feature that we will examine soon.
Important limitation: this solution only works using March's IP cameras and March's VMS (not March's DVR appliances).
This looks to be a useful feature that demonstrates benefits of using on-board storage in IP cameras.
[Update 2012: Edge Storage use is accelerating and becoming one of the top trends.]