Network video recorder is the core component for IP-based video surveillance system. An enterprise-grade NVR can support high quality real-time video/audio monitoring, megapixel resolution recording, and playback from multiple IP cameras. Generally, an Enterprise-grade NVR also can be used as a network video server. It is based on high performance hardware + advanced video management software. It's usually a enterprise grade computer which may use Quad-core processor and up to 8GB DDR3 memory. The NVR is capable of recording videos from up to 64 IP cameras, delivering exceptional performance with up to 450 Mbps throughput to ensure stable recording of multiple megapixel IP cameras.
Enterprise-grade NVRs support all the functions and features what embedded network video recorders have. The enterprise grade NVR has capability to handle much more IP cameras than embedded NVR, it provides highest RAID level for data protection. Moreover, some enterprise-grade NVR supports dual OS embedded on the DOM architecture to ensure that the system boots up and operates stably. It has smart fan to deliver system heat dissipation with minimum vibration. Some high-end models feature a redundant power supply to ensure maximum system uptime. For medium and large network video surveillance projects, enterprise-grade NVR is the ideal equipment for video surveillance central monitoring.
In previous paragraph, we mentioned the RAID, what's the RAID? When any hard drive perform reading and writing, there is a high risk of failure. RAID stands for redundant array of independent disks, which is a data storage virtualization technology that combines hard disks to achieve redundancy, greater speed or both.
RAID levels and their associated data formats are standardized by the Storage Networking Industry Association (SNIA). RAID comes in elves 0-6. The most common RAID levels used in video surveillance recording/storage are 5 and 6.
RAID O level provides no data redundancy for handling disk failures, it only increases the speed of data writing and reading. RAID 0 consists of striping, without mirroring or parity. The capacity of a RAID 0 volume is the sum of the capacities of the disks in the set, the same as with a spanned volume.
RAID 1 mirrors all data to two or more drives without parity or striping. Multiple pairs of mirrored hard drives can be striped together in a RAID 10 or a RAID 1+0 array. This is the most fault tolerant RAID setup since all data is mirrored fully, however since it requires twice as many hard drives to provide the needed capacity, it’s typically used only for operating systems or programs. RAID 1 is rarely used for storing large amounts of surveillance video.
RAID 2 and RAID 3 consist of byte-level striping with dedicated parity. All disk spindle rotation is synchronized and data is striped. Unfortunately, RAID 2 and RAID 3 level are not commonly used in products.
RAID 4 consists of block-level striping with dedicated parity. This level was previously used by NetApp, but has now been largely replaced by a proprietary implementation of RAID 4 with two parity disks, called RAID-DP.
RAID 5 and 6 are widely used to store large video surveillance video data.
RAID 5 consists of three or more disks that provide redundancy and increase speed. RAID 5 allows you to fault one disk, this means when you lose a drive, your system will keep running. When you replace the drive, the data will be rebuilt with the information that was on the missing drive. It should be noted that if a hard drive is replaced, the system likely still be vulnerable to data loss because it takes time to rebuild the entire lost data volume. Additionally, the system is unable to generate new parity data until the data on the hard drive has been rebuilt.
RAID 6 consists of block-level striping with double distributed parity. Double parity provides fault tolerance up to two failed drives.
(RAID 10 is nested RAID level, also called hybrid RAID, this RAID technology combines two or more of standard RAID levels to gain performance)
Many people think RAID is foolproof, this is a common misconception. Unfortunately, disk failure is possible to happen all at once or over time. If the administrator isn't properly monitoring the server for disk failures, disks can fail over time causing the array to fail. Generally, the more disks that you have in your array, the higher possibility of failure. Although RAID 5 and RAID 6 redundant technology do offer some scales in protecting the data, it's highly suggested that people also backup their data, especially if the data is important.
What RAID level should I use? Whether you choose to implement RAID depends on your own requirement. You can ask yourself whether you need to have redundancy and/or high speed access, or the recorded video data is very important and needs to be available at all times.
If your answer is no, then you can use single drive. Therefore you can get more storage for the same price because all of your space will be realized. However, if you answered yes and the data you need is important, then using RAID with a backup is one recommendation.
For important data, some may choose one or more of these options:
1. Record data to two servers that are in a RAID simultaneously. If something goes wrong with one server, the other will have the data intact and will be recording.
2. Bump the RAID level to 6 or a combination of different RAID levels. With a RAID 6, you increase the redundancy factor and can have two disks fail, but here is also the speed factor because it writes data to multiple disks at once. Please note RAID 6 takes up more space compared to RAID 5, so there is a trade-off of losing space, but increasing your security.
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