PaulyP

Hi When you say it will only run 4 at 8 megapixel I assume you are talking about the live decoding specifications. As I understand it the boxes are able to record cameras up to 12 megapixel with the incoming bandwidth of up to 320 Mbits. As these cameras are limited to 16 megabits then the box should be able to handle / record 20 of these 8 megapixel cameras. Only 4 would be able to be viewed live at 8 megapixel or we could view 16 of them at 1080p. We are not really that interested in viewing the footage live, it is more important to have recorded footage in 8MP in the event any of our units is broken into or damaged so that we can go back and look at the footage at a later date. Our security company will only be monitoring a couple of the cameras - mainly the ptz cameras in the event that one of the alarms goes off. Given that as it seems to me the box can record the 20 x 8 megapixel cameras and only view 16 at 1080p we had looked at putting two boxes in to divide the cameras between them so that each box is doing less work and for some redundancy should one box fail. Have I understood that correctly? Would you be good enough to explain why the two 2 megapixel H. 264 cameras would be a problem? We are a business support organisation with 24 properties that we use to help businesses start up and develop. Many thanks again for your help Paul

Hi, Hope this is the right place to post this. I have designed a new CCTV project for one of our sites and need a little advice regarding the hard drives to use. While looking at the hard drive options I came across the annual workload rate for the hard drives. Looking at the Western Digital Purple HDs, it states that these have a workload rate of up to 180TB/year. This got me thinking as to how much our hard drives would actually be subject to over the full year and so I went on an online storage calculator with the settings as below: https://www.aventuracctv.com/calculator/hard_drive_calculator.asp 24 x 8MP cameras H265 20FPS Highest Quality 16384kb/s bit rate 24/7 hours recording 365 days (to calculate total amount written to drives over the year) This gives a total annual storage (or amount being written to the drives over the year) as 1513TB (I suspect it would be a bit lower as I guess the cameras wouldn’t use the full 16k bit rate when there is little motion in the scene – so this is worst case scenario). The WD Purple drives only have a workload rate of up to 180TB per year. So 4 drives would give us annual written data within spec of 720TB/Year (4 x 180TB each). That would mean we would go through a year’s workload in only 5 months. I assume this would void the warranty? Therefore we’d need to have at least 9 Purple Drives (9 * 180TB = 1600TB) to be within the stated spec of the hard drive and be within the warranty limits. Alternatively Western Digital list on their website on the Surveillance Storage page a Gold Enterprise Class Hard Drive. These drives are rated at 550TB workload per year (3 x higher than the Purple Drives) so just 3 of them would be within the tolerance of the up to 1513TB recorder per year. Having 4 of them would mean each drive was only being used 68% of there maximum workload and so would have no issues with warranty. There are other advantages as well to the Gold drives as below: Spec.......................Purple Drives..............Gold Drives Workrate.................180TB/yr....................550TB/yr RPM Class................5400..........................7200 Cache....................64MB.........................128MB Warranty.................3 Year........................5 Year AllFrame 4K Tech......Yes............................Not Specified Price (For 6TB).........£132..........................£172 (exc vat) At only £40 per drive more it seems like the Gold drives are the better option especially given the 5 year warranty. However, although WD list the Gold Drive on their surveillance page, they make no mention of this “AllFrame 4K™ technology for system playback and performance”. This tech is described as: "AllFrame 4K technology enhances ATA streaming support to help reduce video frame loss with proprietary cache policy management technology to improve overall data flow and playback. WD Purple 10TB HDDs include exclusive firmware enhancements that help protect against video pixilation and interruptions within a surveillance system." Now I don’t know if 4K Tech is irrelevant for the Gold drives being 7200rpm vs 5400rpm for the Purple and a larger cache but I can’t find out from anywhere - there doesn't seem to be a way to ask WD directly. The purple drives are designed specifically for NVRs but Gold are a much higher spec drive being enterprise class (and their Premier Drive) and so may be superior still than the Purple ones for NVR use. If Gold performs as well as or better than Purple then for the small price difference it seems Gold is the better option. Thanks for any help and guidance. Paul.

Thanks for your reply. I'm not trying to store footage for a year... only a week to begin with. I can add more HDD's at later if I need to. The cameras however will be constantly recording over the top of previously recorded footage and so I was using the 365 days more as a calculation for the amount of information that was consumed by the HD over the year rather than the amount I was actually looking to store. We're looking at 8MP Hikvision Bullet Cams with 2 x 2MP PTZ cameras. All the equipment is h265 including nvr except for the 2 ptzs. 2 of these NVRs https://www.hikvision.com/uk/Products/Network-Video-Recorder/9600/DS-9632/64NI-I8 The cameras are limited to 16Mbit per second so the storage calculator will be giving me worse case scenario figures with lots of movement on all cams at once which is unlikely. We're looking at starting off with 24 terabytes of storage which the storage calculator said would give us (worst case scenario) 5 days of stored recordings which I was taking a wild guess would be possibly more like 8 to 10 days in real terms use. My main query is really whether the Western Digital gold hard drives are as good as or better than the purple hard drive for nvr use as I would prefer the longer warranty. Thanks. P.S. it's commercial use.