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Judging from the popular tags, I may have the wrong stack exchange. If that's the case, could someone point me to a stack that could help with this. Anyways...

I was just wondering what the data storage costs would be for an ideal scenario of body-worn camera (BWC) use by police officers. By "ideal", I mean a situation in which every single officer on the job has a BWC on them and recording at all times while on duty, and the data is stored for at least a year before deleting.

I calculated how much data departments would generate using the information given here which says that 4k@60fps uses 750MB/mn.

Next I used the number of sworn-officers in a department, divided it by 3, because there are 3 shifts in a day, then rounded up to the nearest whole number. While I know that some shifts are larger than others, I think it should all average out, so more officers on one shift means that there will be less on others. Next, I assumed each shift was 9 hours, making for 27 working hours in a day. So, I multiplied the number of working hours in a day(27) and multiplied that by the number of people on each shift. This got me the total number of recording hours for a department in a day. Next, I just had to multiply the total number of working hours by the data used by each format. I was dumbfounded at the amount of data storage this would require.

For a department with 10 officers, they produce 1.7739 PB/yr. A department with 50 officers would require 7.54PB/yr. Larger departments' numbers are staggering. For a department with 2,000 officers, they would produce 295.8PB/yr. Chicago PD, with 11,900 officers, they would produce 1,759.27PB/year. The NYPD, with their roughly 35,000 officers, they would produce 5,174PB/yr. And, if all 800,000 officers in America were equipped with 4k@60fps bodycams, officers would produce a tremendous 118.26ExB/yr. For comparison, the total amount of data stored in data centers worldwide in 2021 is 1,320ExB So, obviously, this is a LOT of data being generated. And that brought me to my question:

How much would storage for this amount of data cost?

I tried figuring this out on my own, but I believe I am ill-equipped to answer this. The largest amount of storage I could find a price for, was on a single PB. The on-site costs for a single PB over 5 years came out to 1.97M.

This calculation covered one Dell EMC Unity 400 Hybrid Flash Storage for 500K. 500K for the maintenance contract with Dell for support of the system. Then, 50K for ancillary maintenance... as a side note, if someone could explain why you have to pay half a million dollars over 5 years for factory maintenance, why would you end up spending an extra 10K each year on other maintenance, that would be awesome. What would that entail? Anyways, the other costs are 50K for ancillary hardware and software; 120K for power and cooling; and 750K for personnel. Making a yearly cost for everything 394K/PB/yr.

According to the same article as above, it says says storage costs would be 5.99/TB/mo. or 359.4K for 5 years. Then it says that you would still need personnel to manage your data, but less. Since this is a sales pitch, I'm going to assume they're lying, and just add the same costs for personnel that they used for in-house storage. So, I added 359.4K, which would be the actual 5-year cost, to 750,000 to get 1,109,400 for 5 years of the cloud storage, or 221,880/PB/yr.

Figuring how much storage would cost based on these figures is trivial. Using these figures, I get utterly astronomical costs. A department of 50 would cost almost 3M for in-house storage and over a million and a half for the cloud. A department of 500 would need to be spending almost 30M for in-house, or 16.4M for cloud storage. Chicago PD would need to spend almost 700M for on-site storage or almost $400 million for cloud storage. NYPD's data storage costs over 2B for in-house storage and a little over 1B for cloud storage. For the storage of all police footage in America, we’re looking at OVER 46B for in-house storage, or more than 26B for cloud storage.

All this being said, I imagine, like most things, as you scale up, cost per unit goes down. My first clue about this was that on Dell’s website for the EMC Unity 400, it is listed as “EMC Entry and Midrange”. There are other storage drives that claim to hold 3.59PB, but you have to contact them for a quote. I did, and didn’t get a response. That’s why I’m here. I am pretty sure the costs would go down as you scaled up, but I have no idea by how much. So, I was hoping that someone who has experience with a large data center could help.

I tried looking how much data centers cost and the rough estimate I found was $1,000 per sq. ft.. Then according to the Wasabi Cloud Storage web page, it says that that 1PB system will take up two racks, which would be about 20 sq. ft. This allows me to again do incredibly rough estimates. For example, for all police footage, the ~119ExB storage facility would need to be 2.38M sq. ft. or a cost of 2.38B. However, I imagine that data centers allow for stacking, which could drastically reduce the size of the building, but again, by how much, I do not know.

In researching this, I was hoping to find how much data a data center can hold, and I found a Quora answer that gave a figure of 470TB per sq. ft. This brings the required size for the 119ExB facility down from 2.38M sq. ft. to 253.2K sq. ft. So, the cost comes to 253.2M.

Now, I am not sure how accurate these numbers are. So, my questions are covering different scenarios. How much would it cost for storage of: 8 PB (50 officers)

75 PB (500 officers)

150 PB (1000 officers)

300 PB (2000 officers)

1,760 PB (Chicago PD)

5,200 PB (NYPD)

120,000 PB (all police)

This includes all racks, cables, servers, air conditioning, housing, personnel, etc. Thank you so much for any clarity you could provide.

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  • $\begingroup$ "which says that 4k@60fps uses 750MB/mn": okay, but who says police uses 4k@60fps recordings? "making for 27 working hours in a day": there's only 24 hours a day on earth, so this is nonsensical. 3 shifts a day at 9 hours each (assuming one hour break, filled by another officer) makes for 24 hours/day. Note that 4k@60fps is not always that large. It depends on bitrate and format (e.g., HEVC vs H264). I also assume body cams won't see much difference from frame-to-frame, so there could be optimizations in storing I-P-B frames. $\endgroup$
    – fejyesynb
    Commented Apr 21, 2022 at 21:12
  • $\begingroup$ @fejyesynb 4k@60 is a best-case scenario, not something I expect. And, 750MB was chosen because it was the largest number I could find. Next, I chose 9, because I averaged 8 and 10-hour shifts. Lastly, if you have 3, 9 hour shifts, there will be 3 hours of the day during which you have 2/3 of your force on instead of 1/3, this amounts to an extra hour of day. $\endgroup$ Commented Apr 22, 2022 at 3:45
  • $\begingroup$ @fejyesynb I meant to ask you in my last comment, but I forgot, what did you mean by "optimizations in I-P-B frames"? I don't know what that is. $\endgroup$ Commented Apr 22, 2022 at 5:33

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This is a good questions but any standardized answer is basically a guess. Just a couple of confounding variables and considerations:

Unlike the inference from above, officers don't record all the time. So the 9 hours of recording is an overestimate. Activation of BWC may be more in the range of a couple of hours per shift if that. This will depend on the agency's policy, practice, and activity level. Most departments require activation for interaction with citizens, but how they operationalize this varies considerably Some require activation of BWC and dispatch but other as at citizen contact. Activation at dispatch would add footage time, all other things being equal. The additional footage amount would vary by agency. In an urban department where time-to-arrival (t-t-a) is minutes the addition would be negligible in a remote rural area t-t-a would be substantially more.

  • Storage of BWC footage as prices by most BWC vendors is not the same as storage of other videos. "Storage" in the case of BWCs is really the combination of storage, access, retrieval, and management of BWC data.

  • BWC vendors are moving away from al a carte pricing (you pay $X for the camera and $Y per terabyte of storage to video-as-a-service (Vaas), which may be an agency pays $Z per BWC per month with unlimited storage and replacement of hardware every time there is an equipment upgrade over the 5 year contract period.

Those are just a few of the variable in a dynamic and complex BWC ecosystem that make cost estimates difficult, not just about storage but about any aspect of BWCs programs.

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  • $\begingroup$ I appreciate your insight, it helps a little. As the question states, this was a best case scenario. I understand that cops use their BWCs much less than 100% of their shift; however, considering that BWCs have caught misbehavior during times when the cameras would typically be off, I was trying to figure out the cost for BWCs being on at all times. The hope was that a data systems engineer with experience in large data centers could provide approximates. $\endgroup$ Commented Jan 27, 2023 at 19:26
  • $\begingroup$ Got it. The technical questions and the ethical and practical questions overlap. Worth noting that BWC generally runs all the time in "buffer mode." If the officer hits the record butter, then a time span before that start is saved with the recorded span of video. That time span is typically programmed at 30 seconds or a minute. Sound is not recorded in the buffer (not sure why). Running the BWC for a full shift may drain the battery before the end of the shift. It also may make officers more reticent to use BWCs, basically seeing them as "big brother." $\endgroup$
    – John
    Commented Jan 29, 2023 at 14:00
  • $\begingroup$ Yes, I am quite aware of the fact many BWCs have a "pre-record" function that copies video from before the on button was pushed. This function has caught NYC, LA, and Baltimore cops planting evidence. Also, I found a BWC with a recording battery life of 14 hours, so I am not concerned about that, also battery swaps if necessary are no big deal. As for cops not wanting to wear the BWC, I don't care. It's not up to them. Most leaders in major police departments see BWCs as an aid, not an impediment; if they do, it's likely they are trying to hide something. $\endgroup$ Commented Jan 29, 2023 at 22:49

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