How to Build a Highly Available Storage Solution for NVR Applications. Bruce Chen Project Supervisor Moxa Inc.

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1 How to Build a Highly Available Storage Solution for NVR Applications Bruce Chen Project Supervisor Moxa Inc.

2 NVR systems need to store large video files, so data storage is a central system requirement. Network Video Recorder (NVR) systems are now widely used in surveillance and security applications, such as building/factory security or rolling stock video surveillance. Because NVRs need to store digital video files, they tend to come with substantial data storage requirements. Mass storage devices such as USB flash drives, SD memory cards, or hard disks can be used to provide the necessary storae capacity. To get an idea of the requirements of NVR systems, let s look at a common surveillance application, an IP-based train surveillance system. The system uses cameras located throughout the train to record video, has a network of Ethernet switches, and uses computers to operate the cameras and store video data. Video servers may also be used if there are analog cameras in the system. A system display is available in the driver s cabin for realtime video monitoring or video playback of specific files stored on the computers. Data storage is a key limitation of this type of NVR system, because the entire surveillance system generates a large amount of video data that must be saved for potential review later. In addition, the train often must operate independently, because it is a fast-moving application platform that may not have a secure link with the ground-based network. This means that the NVR storage should be as self-sufficient as possible, and not rely too much on constant off-site storage backups. However, mobility of rolling stock applications poses a separate challenge for the NVR data storage: this is an environment with high vibration and shock, which is a very problematic environment for fragile hard drives to operate in. Released on March 18, 2011, all rights reserved. Moxa manufactures one of the world s leading brands of device networking solutions. Products include industrial embedded computers, industrial Ethernet switches, serial device servers, multiport serial boards, embedded device servers, and remote I/O solutions. Our products are key components of many networking applications, including industrial automation, manufacturing, POS, and medical treatment facilities. How to contact Moxa Tel: Fax: Web: info@moxa.com This document was produced by the Moxa Technical Writing Center (TWC). Please send your comments or suggestions about this or other Moxa documents to twc@moxa.com. Copyright Moxa Inc. 1

3 Major Challenges in Existing NVR Storage Systems It is difficult for NVR systems to deliver the right combination of storage capacity, vibration/shock resistance, and ease of maintenance at a reasonable cost. This difficulty is compounded for NVRs on moving vehicles. Storage Capacity: Delivering sufficient storage capacity is a major challenge in deploying today s NVR systems. NVR systems that continuously record video require significant storage capacity, and a higher video resolution requires more hard disk capacity. In addition, hard disks need to be replaced, especially if the system is required to maintain a long-term video record. A long-term video surveillance database can be a valuable resource, but to keep this kind of record, hard drives that reach their storage limit will need to be pulled and archived, and then replaced with new hard drives. This can be a time-consuming procedure that substantially increases system maintenance overhead and costs. Vibration and Shock: Vibration and shock is a constant challenge for NVR systems, particularly those deployed on moving vehicles such as trains or buses. Commercial-grade storage media, such as hard disks, cannot withstand the movement and shock that is commonplace on moving vehicles. Vibration and shock can lead to system instability and reduce the lifecycle of the equipment. The most common approach to address this challenge is to use industrial-grade hard disks or solid state drives (SSDs), both of which are extremely expensive compared to commercial hard disks. The price of SSDs also affects how much storage capacity system operators can afford, compounding data capacity limitations in a system that is probably already starved for more data storage. Maintenance: Maintenance is another ongoing challenge for NVR systems, and is related to the two challenges listed above. Storage devices that must be repeatedly replaced impose substantial maintenance costs. In addition, the system must be shut down during the hard drive replacement process. However, insufficient storage, or constant vibration and shock damage, can lead to unsustainable replacement cycles. Imagine a train that has been running for hours which has finally reached its destination and is ready for some maintenance. The train s NVR system has been recording independently to local storage, because no consistent link with the trackside network as available. At this point maintenance engineers must check the system storage capacity and replace the hard disk if needed. In a conventional embedded computer, this procedure is laborious and time consuming. First the engineer must power off the computer. Then he must use a screwdriver to remove the case. Then, he needs to use the screwdriver again to remove the hard disk. And then he still must reverse all of the steps above to install a new hard disk! Because hard disk replacement is such a tedious task, it is a costly and time-consuming part of the maintenance cycle. For NVRs on moving vehicles, maintenance can only be performed when vehicles are not running, which decreases the overall uptime and efficiency of the broader transit system. Highly Available NVR Data Storage in Demanding Conditions New technology can overcome the common obstacles that confound NVR systems, and do so in a way that improves costeffectiveness, efficiency, and system performance. Hardware that Enhances Vibration and Shock Resistance: Solid state drives (SSDs) are one way to create systems that can 2

4 withstand the vibration and shock experienced by applications on trains and buses. However, this solution is very costly, especially in systems that need high storage capacity. Adopting SSDs can lead to unaffordable systems, or to compromises on storage capacity in order to keep costs down. An alternative and improved solution is to employ a hardware design that reduces the impact of vibration and shock so that commercial-grade, cost-effective, and high-capacity hard drives can be used without reservation. This will increase the costeffectiveness of the system without compromising on reliability or storage capacity. Moxa s design engineers applied the laws of physics and asymmetrical design principles to design a hard disk protection mechanism for Moxa s railway computers that absorbs vibration and shock. This solid theoretical design was then subjected to practical real-world testing, verification, and refinement that yielded constant iterative improvements. Prototypes of Moxa s computers are subjected to a battery of sophisticated and meticulous testing to optimize the placement of all hardware components and minimize the impact of vehicle movement. An asymmetrical hard drive bracket reduces the effects of vibration and shock Simpler Drive Replacement: Because hard drive replacement can become such a huge part of the overall maintenance workload, increasing the simplicity and efficiency of just this one task can go a long way. A drive that is hot-swappable can be replaced without turning off the computer. A similar convenience is a drive tray, which allows the technician to remove, replace, and install hard drives without using any extra tools. Moxa s V2416 embedded computers include a drive tray that allows maintenance staff to quickly replace hard drives. Additional software development allows this hard drive to be replaced without even shutting down the computer. The crucial element is the V2416 s programmable button and LED indicator. The button and LED can be customized by the end-user to automate commonly performed tasks. For example, the button can be configured to unmount the hard drive, with confirmation from the LED indicator. By using these features, the technician can unmount the hard drive with a button press and replace the hard drive without any complex modification of the computer s software configuration. 3

5 Hard drive trays simplify drive replacement, a common NVR maintenance task The button and LED can be customized to streamline other commonly performed tasks as well. For example, the button can be programmed to automatically perform a system backup, or to automatically transfer certain files to another computer on the network. The LED indicator can be programmed to provide needed system alerts, such as when storage capacity is low, or when the hard drive is unmounted and ready for removal. Moxa s Reliable and Powerful NVR products Moxa s video products deliver the reliability, industrial certifications, and unique technology needed to overcome common NVR obstacles. Moxa s V2416 embedded computer is a powerful and versatile platform that is both rugged enough to withstand vibration and shock and advanced enough to include time-saving technology such as hot-swappable disks. Moxa also provides video servers and camera products that are designed specifically for the rigors of industrial and vehicle-based NVR systems. Review product specifications or request a price quote at and visit store.moxa.com to quickly order sample products. Disclaimer This document is provided for information purposes only, and the contents hereof are subject to change without notice. This document is not warranted to be error-free, nor subject to any other warranties or conditions, whether expressed orally or implied by law, including implied warranties and conditions of merchantability, or fitness for a particular purpose. We specifically disclaim any liability with respect to this document and no contractual obligations are formed either directly or indirectly by this document. 4