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RAID options in Video Surveillance

What is RAID? – RAID is an acronym that stands for a Redundant array of independent disks. The main objective of Raid is to add redundancy and/or increase performance. In the Video surveillance industry, this translates to secure video recordings without compromising the performance by adding fault tolerance of the HDDs. The relevant to our industry RAID options and the ones to be further explained are RAIDs 0, 1, 10, 5, and 6.
RAID 0 increases and improves performance by dividing the read or write traffic between at least 2 disks. RAID 0 is performance focused by maximizing the reading and writing operations while also being simple to use. It can also be used to combine multiple disks into a single logical volume. However, with its focus being performance, there is a lack of tolerance for any faults. This translates to it not being utilized for mission-critical systems or data. Most ideal for non-critical data storage that must be read and written quickly such as video/photo editing systems.
RAID1 focuses on reliability by mirroring the data, with at least 2 disks. This translates to redundancy being maximized. Since data is mirrored, it becomes easy to access information that has frequent traffic while also providing easy repairs without losing video. Hot swap HDDs make the replacement a very simple process. The drawback to it is you only get half the storage for every drive you integrate, without significant performance boosters. Furthermore, it is trustworthy in case of any hardware/human failure, which means it is ideal for users relying on it for the most critical data. Most appropriate when used for mission-critical parts of the system with less intensive requirements for space such as the operating system, the software application, and databases.


How about combining Redundancy and performance? RAID 10 mirrors while also dividing data between at least a 4 disks array. It is a nested combination of RAID 1 and RAID 0. The system divides the data between 2 disks, while the other 2 mirror the stripped disks storing half the data. You get double the performance while also being able to withstand the hardware failure of up to 2 drives, without losing data. The repairing of the data in the new disks is also efficient and quick to restore. The drawback can come from the result of mirroring, which consumes half of the storage space. In video surveillance /security systems, RAID10 is suitable for hosting the databases of the VMSs, Access Control, etc.
RAID 5 is fast for reading data, as well as storage efficient while being spread through at least 3 separate disks and while using parity. Parity is used to rebuild data and recover from a hardware failure. With the current HDD sizes above 10TB, the greater RAID rebuilding time (up to several hours) could be an issue since another potential HDD failure will lose all the recorded video. Great for large amounts of data. RAID 5 can be quick at reading data, whereas writing data operations can be a little slower. For instance, in the case of 100% writing operations, it takes a RAID 5 with a minimum of 4 HDDs to equal the IOPS of a single HDD of the same model. We suggest using RAID5 for more than 4 discs (due to performance) and less than 10 (due to RAID rebuild times) for video surveillance.
RAID 6 is complex and is for larger arrays of hard drives while providing similar principles as RAID 5. Needs at least 4 disks of storage. However, RAID 6 has the capacity of withstanding the failure of 2 disks in case of failure without data loss, making it more fault tolerant than RAID 5. This is possible due to the double parity on each disk in RAID 6. However, this can also affect the writing performance compared to RAID 5; about 20% slower as a product of the double parity. Provides redundancy without performance upgrades from RAID 5. We suggest using RAID 6 in all cases with more than 10 drives.

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