RAID

RAID stands for Redundant Array of Independent Drives/Disks. RAID is a software (or sometimes hardware) feature that turns a set of independent disks into a single array, in basic terms sharing data between the disks.

RAID is primarily used as a form of gaining redundancy in the event of hard drive failures. So that in the event your hard drive fails you will not lose any recordings .There are many levels of RAID which dictate how much storage is available and how much hard drive redundancy there is.

NVR Support

Only SCW’s Imperial line of NVR’s support RAID functionality.

RAID Levels

RAID 0 - Striping

Fault Tolerance: None

Hard Drives Required: 2+

RAID0 is typically used in situations where disk speed is a major requirement. RAID0 is not recommended for security camera applications because if a single disk fails your entire array fails - which means losing all the footage. Basically - don’t use RAID0 for security cameras.

RAID1 - Mirror

Fault Tolerance: One or more drives

Hard Drives Required: 2+

RAID1 is typically used with just two hard drives. In a RAID1 configuration data is mirrored across the drives. So data chunk A is stored on Drive 1, 2, and any sequential drives after. RAID1 means that if one hard drive fails, you still retain all your data.

RAID1 also means that you essentially cut your storage capacity in half or more. For example, with two 10TB drives, instead of having 20TB available for storage, only 10TB would be available. This is because both drives retain the same data.

If you are adding a third or further drive to RAID1, this will simply expand the fault tolerance to two or more hard drives, but not expand the amount of storage available. For example, if you have three 10TB drives, you will still only have 10TB storage available, and now two disk fault tolerance.

RAID5

Fault Tolerance: One Drive

Hard Drives Required: 3+

RAID5 is one of the most common RAID configurations for security cameras due to the balance between fault tolerance and storage capacity.

RAID5 “takes” one drive to give you one drive of fault tolerance. For example, if you have 3 10TB drives, you would have 20TB of capacity and 1 disk loss tolerance. If one drive fails, you do not lose any data.

RAID5 also scales to any drive 3 and above. So if you have 5 10TB hard drives you will have 40TB of available storage and still retain one disk fault tolerance.

However, in the unlikely and unfortunate circumstances of two hard drives failing or becoming corrupt at the same time - no data would be retained.

RAID6

Fault Tolerance: Two Drives

Hard Drives Required: 4+

RAID6 requires at least 4 hard drives and offers two disk tolerance at the expense of two disks. For example, 4 10TB hard drives would give you 20TB of available hard drive storage but two disks can fail before data is lost.

RAID6 also scales up beyond 4 drives as well. So you could have a system with 8, 10TB drives, and have 60TB for storage and two disk tolerance.

RAID6 is a great option for those who want greater fault tolerance over RAID5 but still utilize disk capacity.

RAID10

Fault Tolerance: One Drive

Hard Drives Required: 4+

RAID10 offers a read and write speed boost, one disk redundancy, at the cost of half the hard drives.

For example, if you have 4, 10TB drives, 20TB would be available for storage capacity. If you have 6, 10TB drives, only 30TB.

RAID10 isn’t commonly used in security camera applications.

Rebuilding RAIDs

In the event of a hard drive failure in a RAID, outside of RAID0, your recording will be preserved.

RAID Best Practices

RAID setups can be especially sensitive to brownouts, improper shutdowns, and other unexpected power loss. Brownouts and other power issues can lead to data corruption, which can cause the RAID array to need to be completely rebuilt - losing all data/recordings.

It is absolutely essential that NVRs using RAID be on a UPS/Backup battery or some other form of power backup. When rebooting or shutting down the NVR, be sure to power down properly using the menus on the NVR, do not just flip the switch or unplug the unit.

Conclusions

All RAID levels offer a mix between data security and drive costs. It’s important to evaluate what level of fault tolerance is required or acceptable in your unique application.

Arguably, the most suitable RAID configurations for video surveillance are RAID5 or RAID6. Both offer a balance between protection and disk availability that allows you to store large amounts of footage while protecting against a disk failure or two.

If you have questions about RAID and which RAID level is best for you - contact the team at SCW and we’ll be happy to help!