Per-Entity Metadata Working Group

[Nick Roy <>]

On 9/14/16 12:27 PM, Tom Scavo wrote:
> On Wed, Sep 14, 2016 at 1:45 PM, Cantor, Scott 
> <>
>  wrote:
> > On 9/14/16, 12:20 PM, 
> > "
> >  on behalf of Tom Scavo" 
> > <
> >  on behalf of 
> > >
> >  wrote:
> >
> > > 5) What is our failover strategy?
> > Can you explain what you mean specifically?
> Yes, I'll try. First, factor out the CDN. It doesn't have anything to
> do with what I'm about to say.
>
> The best way to motivate the question is to review our failover
> strategy for aggregate distribution (md.incommon.org). There are two
> servers behind md.incommon.org: a primary (here in Ann Arbor) and a
> hot spare (in Indiana). We manually fail over to the hot spare when
> necessary. Clients never notice when we fail over since that is the
> nature of aggregate distribution.
>
> For per-entity metadata, it's a totally different story. Fail over
> needs to be automatic, and the various servers need to be
> strategically located in geographic regions such that latency is
> minimized (or at least acceptable).

That is exactly why having at least one CDN, and preferably more than 
one, is relevant to a failover strategy.  Geographic and logical 
redundancy.  Publishing to more than one CDN than one means you can 
configure clients to fail over between more than one service.  Keeping 
the naming separate and putting the failover between CDNs in the client 
lets clients specify parameters they are comfortable with for things 
like latency.

Nick

> Does that help?
>
> Tom