Many Dahua recorders (DVR, NVR), including the OEMs, support the RAID feature. In a few words, RAID is a storage technology that is used to organize multiple hard drives into various arrangements to meet certain goals like redundancy, speed, and capacity.
RAID can be categorized into Software RAID and Hardware RAID. In software RAID, the memory architecture is managed by the operating system. Dahua uses the software RAID model.
In this guide, we’ll explain the terminology used in the Dahua RAID settings and clarify a few things regarding the RAID error codes. The guide is valid for Dahua DVRs, NVRs, and their OEM product line on brands such as Activecam, Advidia, Amcrest, Ameta, Ascendent, Backstreet Surveillance, BV Security, CCTV Security Pros, CCTV Star, CP Plus (Orange Line), Dax Networks, eLine, ENS (formerly Eastern CCTV and SavvyTech), Expose, Lorex, GSS, Honeywell, IC Realtime, Ikegami, Impath Networks, Inaxsys, IndigoVision, Infinity CCTV, Innekt, Intelbras, KBVision, Lumixen, Maxron, Montavue, Oco, Optiview, Rhodium, RVI, Saxco, Security Camera King (Elite), Space Technology, Speco, ToughDog, Tyco Holis, Tyco Illustra Essentials, Unisight, VIP Vision, Watchnet, Winic, Zuum.
Dahua RAID Errors Explained
The RAID state is calculated by this formula: d (>) or (=) or (<) n-1.
- D (disks/hard drives): Number of active/working hard drives
- T: The total number of the hard drives in the RAID
For example, a RAID 5 with 5 hard drives and only 3 are working with 1 hot spare, (D=3; T=5). So we have, 3<5-1, which means RAID is Inactive and data is lost
The terminology is explained as follows:
- Active: Raid is in operating condition. The state is calculated by: “D>T-1”
- Degraded: HDD has degraded or no longer operating. The state is calculated by: “D=T-1”
- InActive: Raid is corrupt and data is lost. The state is calculated by: “D<T-1”
- Active, Degraded*: This means one of the hard drives has an issue. Depending on the extent of the issue the hot spare will replace the disk with issues. In the event no “Hotspare is available” should another hard drive fail the RAID5 will fail and become InActive and data will be rendered unrecoverable.
- Active, Degraded, Recovering*: The raid is being rebuilt/rebuilding a disk. In the event, another hard drive fails while in this state data will be lost and the RAID state will change to inactive. During the Degraded status if the HDD space is 0/0 GB but it is still Active the RAID is still operating but it is rebuilding itself. While the RAID is being rebuilt the system can not save the new video to the RAID.
Note: If your security system is displaying something similar to the image below after completing the RAID Setup, that is normal. Your RAID is working properly.
HDD Status in Raid:
- Sync: Indicates all the disks are currently in sync or are synchronizing. In this state, the hard drives are operating correctly.
- Rebuilding Disk: The data on the hard drive is being rebuilt by calculating data from the other available disk. The data has been lost/corrupted or HDD Hot Spare due to a failed disk. No hard drives can be removed or changed during this time period otherwise will risk the loss of the entire raid.