Table of Contents
- Storage Calculation Formula
- Camera Bitrates Table
- Retention Period Planning
- DVR vs NVR Storage
- Indian Brands and Pricing
- Choosing the Right HDD
- FAQ
Storage Calculation Formula
Calculate CCTV hard disk storage requirements with this formula: Storage (GB) = Cameras x Bitrate (Mbps) x 3600 x Hours/day x Days / 8 / 1024
Example: 4 cameras at 2Mbps each, 24 hours/day, 30 days retention: 4 x 2 x 3600 x 24 x 30 / 8 / 1024 = 3,164 GB. Add 20% overhead for file system = 3.8 TB. Recommendation: 4TB surveillance HDD.
Camera Bitrates Table
| Resolution | Compression | Bitrate (Mbps) | GB/day/camera |
|---|---|---|---|
| 720p HD | H.264 | 1-2 | 10-21 |
| 1080p FHD | H.264 | 2-4 | 21-43 |
| 1080p FHD | H.265 | 1-2 | 10-21 |
| 4MP | H.265 | 2-3 | 21-32 |
| 4K/8MP | H.265 | 4-8 | 43-86 |
H.265 reduces storage by 50% versus H.264 at same quality. Always choose H.265 for new Indian CCTV installations if the DVR/NVR supports it.
Retention Period Planning
- Residential home: 7-14 days sufficient for most incident investigations
- Retail shop: 30 days recommended (theft claims, dispute resolution)
- Bank/ATM: 90 days minimum (RBI regulation)
- Hotels: 30 days (MHA advisory)
- Government offices: 90-365 days per specific department guidelines
DVR vs NVR Storage
DVR (Digital Video Recorder) uses analog CCTV cameras. NVR (Network Video Recorder) uses IP cameras. Both use standard 3.5-inch SATA HDDs. NVR IP cameras reach 4K/8MP versus DVR analog at 5MP maximum – so NVR systems require more storage per camera for the same channel count. Modern Indian home security typically uses AHD/TVI hybrid DVR at 2-5MP per camera.
Indian Brands and Pricing
| Brand | Channels | Max HDD | Price (Rs) |
|---|---|---|---|
| CP Plus CP-UVR-0401E1 | 4-ch DVR | 6TB | 3,500-5,000 |
| Dahua XVR5104H | 4-ch DVR | 8TB | 6,000-9,000 |
| Hikvision DS-7204HUHI | 4-ch DVR | 8TB | 8,000-12,000 |
| CP Plus NVR 8-ch | 8-ch NVR | 2x6TB | 7,000-10,000 |
Choosing the Right HDD
Use surveillance-rated HDDs – consumer HDDs rated for 8h/day fail rapidly under 24/7 CCTV recording. Recommended for Indian installations:
- Seagate SkyHawk: 1-12TB, 180TB/year workload, popular in India (Rs 3,500 for 1TB to Rs 22,000 for 8TB)
- WD Purple: 1-18TB, 180TB/year, AllFrame AI reduces frame loss (Rs 3,800 for 1TB)
- Toshiba S300: Budget option, 1-10TB (Rs 3,200 for 1TB)
Never use: WD Green/Blue, Seagate Barracuda, Samsung Portable for CCTV recording – these consumer-grade HDDs fail within months of continuous operation.
Frequently Asked Questions
Can I use an SSD for CCTV recording?
SSDs have limited write endurance (TBW rating). At 100GB/day continuous write, a 240GB SSD with 80TBW endurance lasts only 800 days before NAND wear-out. Surveillance HDDs have no comparable endurance limit and are designed for continuous write operation.
Why does my 4TB HDD show only 3.6TB in the DVR?
Hard drive manufacturers use decimal TB (10^12 bytes) but DVRs display in binary TiB (2^40 bytes). A 4TB HDD shows as 3.637 TiB. This is normal and not a defect – applies to all brands.
How do I verify my CCTV is actually recording?
In DVR/NVR menu: check HDD status (green = healthy), verify recording schedule (set to 24h or motion), play back footage from the previous hour to confirm. Indian power fluctuations damage HDDs over time – always use a UPS with AVR for the DVR/NVR.
My DVR shows 30 days retention but footage only goes back 15 days.
Possible causes: HDD smaller than calculated, motion recording capturing more motion than expected, bitrate set higher than default, or all channels at maximum quality. Check HDD usage percentage in DVR status – if cycling at 50% capacity, reduce resolution or increase HDD size.
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