4 ms·
<blockquote> Our research led us to conclude that even for the best configurations in the world (yes, that includes Google, Amazon and all biggies), maximum the
by kilburn 16y ago
<blockquote>
Our research led us to conclude that even for the best configurations in the world (yes, that includes Google, Amazon and all biggies), maximum theoretical downtime (for a few users) will be 30 minutes. You cannot possibly escape this limitation.
</blockquote>
You've overestimated your own abilities. "The biggies" don't need to use DNS failovers, they use anycast routing and the like. Therefore, their "maximum theoretical downtime" is probably much lower than 30 minutes...
- paraschopra 16y agoEven with Anycast, a portion of their users will still be routed to old, down server until DNS cache expires. No? I'd love to get clarified as this is a problem we desperately want to solve.
- skorgu 16y agoIANANetwork Engineer but basically with anycasting you can announce a single IP from two different places and different providers will route to whichever is 'closest'. If your datacenter goes down one of those routes stops being advertised and providers will re-route to the next best advertised route. BGP cycle time is variable but way less than 30 minutes in many cases. This presumes you can essentially have two 'active' datacenters, not all application designs allow for this. You can still use BGP as a failover mechanism, just announce the route to your production IP from DC1 and if that dies, announce it from DC2 once you fail over. Again, limited by response time and BGP cycle time but that's faster than DNS.
- paraschopra 16y agoThanks for your info. I researched a bit and it sounds like Anycast is a very expensive option. But, anyway, I agree it could be faster than relying on DNS routing.