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NVR RAID Explained: RAID 1, RAID 5 and RAID 6 for CCTV Storage

Essential Security Supplies

NVR RAID changes how disks provide capacity and tolerate disk failure. It does not preserve every recording against deletion, recorder damage or a wider incident. NZ CCTV projects should choose the recorder's supported RAID mode alongside retention, workload, fault response and an independent evidence preservation process.

Establish recorder support first

Check the exact NVR model, firmware, supported drives and available RAID modes. Multiple drive bays do not automatically mean RAID support. Dahua's manufacturer page for the NVR608-32-4KS2 lists several RAID modes, illustrating why this must be a model-specific check. Do not transfer that capability to another Dahua or Uniview recorder. Confirm current availability and the proposed configuration before making it part of a quotation. The linked NVR608-128 product is a different model from that documentation example; its final RAID configuration must be verified separately.

Calculate RAID 1 capacity

RAID 1 mirrors data. A simple two-drive mirror with two 8 TB drives provides roughly 8 TB before formatting and other overhead, rather than 16 TB. It can tolerate failure of one member while the other remains healthy. Confirm how the recorder reports a degraded mirror and how it rebuilds a replacement. Mirroring increases disk resilience but does not stop deletion being reflected on both disks.

NVR608-128-4KS2 - Dahua - Ultra Series NVR 128ch
NVR608-128-4KS2 - Dahua - Ultra Series NVR 128ch. Genuine supplier catalogue photograph.

Calculate RAID 5 capacity and limits

For an equal-size RAID 5 set, nominal usable capacity is approximately one drive less than the total. Four 8 TB drives therefore provide about 24 TB before overhead. RAID 5 tolerates one member failure, but another failure during the degraded or rebuild period can compromise the array. Assess rebuild time and workload with the recorder supplier instead of assuming the replacement returns the system immediately to full protection.

Calculate RAID 6 capacity and limits

RAID 6 uses capacity equivalent to two drives for parity. Six 8 TB drives provide about 32 TB nominal usable capacity before overhead. It can tolerate two member failures, subject to the array remaining recoverable and the platform operating correctly. The trade-off is less usable space and a different write workload. Compare the actual recorder's performance and minimum drive count before selecting this arrangement.

ST8000VE001 - Skyhawk - Seagate Surveillance Internal 3.5" SATA Drive - 8TB
ST8000VE001 - Skyhawk - Seagate Surveillance Internal 3.5" SATA Drive - 8TB. Genuine supplier catalogue photograph.

Size retention from usable space

Calculate retention after applying the storage layout. At an illustrative total video rate of 64 Mb/s, one day produces roughly 691 GB using decimal units. Thirty days is approximately 20.7 TB before overhead. A nominal raw disk total is therefore not the retention capacity. Use measured bitrate, reserve and the selected recorder's allocation rules. Check what happens when the array becomes full and overwrite starts.

Define replacement and preservation

Set a fault-response owner, a compatible spare process and an approved replacement procedure. Monitor rebuild progress and recorded continuity during the degraded period. Export important footage separately to an approved destination and verify it opens. RAID does not address theft of the recorder, ransomware, fire, accidental deletion or every controller fault. Those risks need their own operational and technical controls.

ST10000VE001 -Skyhawk - Seagate Surveillance Internal 3.5" SATA Drive - 10TB
ST10000VE001 -Skyhawk - Seagate Surveillance Internal 3.5" SATA Drive - 10TB. Genuine supplier catalogue photograph.

Apply the design to the actual project

Put raw capacity, RAID layout and nominal usable capacity in three separate columns. Follow them with the recorder's actual formatted and allocated capacity after installation. This prevents a quotation based on the sum of disk labels from becoming a misleading retention promise. If disks have unequal capacities, obtain the recorder manufacturer's calculation instead of applying the equal-disk examples unchanged. Keep the supported minimum drive count and replacement procedure beside the selected mode.

Define the response to a degraded array before the first fault. Name the person who receives the warning, the supplier of compatible replacement disks and the authorised maintenance window. Check recording performance during an approved recovery test and record any gaps. Preserve important evidence independently before work where possible. A completed rebuild is a recovery milestone, not proof that every historical clip remains present. Review the timeline and exports, then restore normal monitoring and update the disk register with the replacement's exact identity.

Design the recording and network path

Draw the complete path from the camera to the recorder and the operator. Include the switch, uplink, router, time service and every power source. A camera that produces a good live image can still leave gaps in evidence when its stream exceeds the recorder's incoming bandwidth or its network link is unstable. Check recording performance with all specified channels operating together, rather than accepting a successful test of one camera. Record the stream settings used in the trial so that a later installer can reproduce the result.

Retention needs a calculation based on measured bitrate and recording hours. As an illustrative calculation, a constant 4 Mb/s stream produces about 43.2 GB in 24 hours, using decimal units and ignoring overhead. Multiply by the number of cameras and retention days, then allow for formatting, variable scenes and the storage arrangement. This is a sizing example, not a recommended bitrate for every scene. Confirm that movement remains useful in recorded playback at the final settings.

Commissioning acceptance checklist

Agree the expected result before testing. Use the installed configuration and retain evidence of each outcome, including a failure that must be corrected. The following checks supplement the exact manufacturer procedures and the approved project design.

Required check Record to retain
Confirm the supported RAID mode and exact HDD combination in manufacturer documentation. Expected behaviour, actual result, configuration tested and responsible person. Resolve an unexpected outcome before accepting this requirement.
Calculate usable capacity before approving the retention period. Expected behaviour, actual result, configuration tested and responsible person. Resolve an unexpected outcome before accepting this requirement.
Test fault notifications and the documented replacement process in an approved environment. Expected behaviour, actual result, configuration tested and responsible person. Resolve an unexpected outcome before accepting this requirement.

Repeat affected checks after a material equipment, software or site change. Keep the test record with the as-built schedule so the next maintainer can understand which configuration passed and which assumptions still need review.

Equipment candidates and specification checks

These are relevant active catalogue candidates for a project review, rather than a universal recommendation or a promise of immediate stock. Use the full product page and current manufacturer information to confirm the supplied variant and its role in your design.

Review the relevant Essential Security Supplies equipment range alongside the intended workflow. For further context, read our related installer guide.

Frequently asked questions

Is RAID a backup?

No. It primarily addresses particular disk failures and does not provide an independent preserved copy of footage.

Can any multi-bay NVR use RAID?

No. Verify supported modes on the exact recorder and firmware.

Is RAID 6 always the best choice?

The choice depends on supported hardware, usable capacity, workload and the required resilience and recovery process.

Primary references and technical scope

Use the primary manufacturer or technical reference for the claims it covers. General design guidance does not replace the selected product's installation manual. Confirm current firmware, model variants and the approved project requirements before ordering or commissioning.

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Get specification help from Essential Security Supplies

Send your site layout, equipment schedule, intended workflow and any existing model details to Essential Security Supplies for specification help and a project quotation. Identify the functions that must be demonstrated and the interfaces owned by other contractors. Our enquiry route supports a documented equipment review without publishing prices or assuming unverified compatibility.