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Video Storage Array

Introduction
In a couple years I would like to build out a storage array for a hifi video installation. There are three primary goals:

  • Capacity: I would like to store 200 bluray movies, overmargined by 50%.
  • Performance: It must be able to stream unencrypted and remuxed 4k bluray content
  • Cost: In the age of Netflix, it makes sense that this should be dead cheap.

Capacity
200 discs, overprovisioned by 50% is 300 movies.

A bluray unencrypted and remuxed is typically 30GB bringing the total array size to 9TB. In a RAID5 configuration the closest capacity is 8TB. Rounding up to 16TB isn't possible in SSD format at this time, although it could be possible in two years time.

An 8TB array would be a 33% overprovision and when you include the fact that the majority of my first film purchases will be 2k Blurays of much older (and therefore probably lower bitrate due to both being black and white and lower contrast) material I think it would be very possible to store at least 300 movies with an 8TB array.

Performance
I believe most discs are around 30-40Mbps, however I think that is for 2k content and the 4k spec supports 108Mbps.

All SSD on the market today are easily capable of this transfer rate (sustained transfer with empty cache). This is especially true in a 3 disc RAID5 array. Spinning discs probably do not reach this threshold, even in an array.

Cost
As of December 2018, SSD costs have, nearly across the board, fallen to $0.15/GB. This is the lowest it's even been. Let's calculate the cost for a 3 disc RAID5 array.

3x 4TB SSD @ $0.15/GB = 3x$600=$1,800

This is prohibitive. I wouldn't even consider a solution over $1,000. And really does not become feasible until under $500.

A major milestone for SSD cost is $0.10/GB. This would bring cost to $1,200. At $0.05/GB cost is $600. Close, but to hit a target of $500 we will need to see $0.042/GB.

So the holy grail for this project will be 4.2 cents. This is ambitious. If prices fall by 20% per year (total fabrication, but it's been higher if you ignore last year's supply constraint), then it will take almost 6 years before prices reach this level, which is outside the schedule I have for this project.

Conclusion
Capacity and Performance constraints are met at this time. Cost has been the perpetual sticking point for solid state storage. It has made tremendous progress in recent years and I have 3 SSD in my system for this exact reason (one for OS and a 2 disc mirror for music remuxing), but it will be some time yet before SSD are cheap enough for a video storage array.

This will likely lead to a different solution. A 2 disc mirror would meet these requirements for 33% less. This could be cost competitive in 4 years.

If I use a more realistic example of 25 4k bluray, 150 2k bluray, 50 DVD and 33% overprovisioning then storage requirements fall to (25*60+125*30+50*10)*1.33=7.6TB so no help there.

I think I will have to keep my fingers crossed and see where cost goes over the next year.

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