Video: How to Build a DIY CDN
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Read the complete transcript of this clip:
Reza Naghibi: You have hybrid CDNs and multi-CDN architectures. Then some people are actually moving towards private CDNs, DYI CDNs. I have a little diagram here, and that's kind of what a DYI, do-it-yourself, CDN would look like. There are lots of different architectures with configurations. This one we made it so it's a bit more optimized for video delivery.
We've got two tiers, and this is basically just the single location, a single POP, six servers. Let's say you have access to a 100 gig line, we go ahead and split that up into eight 10 gig ports. We go ahead and put two 10 gigs into each server and that gives us about 80 gigs of capacity.
80 gigs of capacity is probably good for, 40, 50, 60,000 concurrent video streams. It could be a lot of streams. It could be a little depending on who you are. We have the disks split up into two tiers. We have the edge tier, which is going to be memory only. Behind the edge tier we're going to go ahead and have a larger storage tier.
We may have, let's say, 256 gigs of memory on each edge tier. For video streaming that's a lot. That's a lot of live streams and VOD. Now the storage tier, we could have, let's say a few terabytes of storage there. Some interesting things here--for example, we have pre-fetch. What we do with pre-fetch is, you know if you are streaming video content, like I said this is very optimized for video. We're going to go ahead and pre-fetch those fragments onto the edge tier.
What's going to happen is like when you DNS into the edge, you know you're basically going to pin yourself to a server. Then what we can do, is we can go ahead and as you're streaming that video, whether that's live or On Demand, we can go ahead and kind of pre-fetch all those fragments there. So that way your whole, your entire video streaming session, you're basically getting, pretty much like 95% cache hits on that server. You're not kind of falling through back to that second tier or even origin.
Let's say you're watching some video that no one else has seen, we can still make sure that, that video is available on your edge.
Varnish Software's Reza Naghibi discusses the pros, cons, costs, and challenges of DIY or private CDNs in this presentation from Content Delivery Summit.