Re: Advise on distributed directory service

[Andrew Findlay <andrew.findlay@skills-1st.co.uk>]

On Tue, Feb 22, 2011 at 05:07:27PM +0100, Germ van Ek wrote:

> Note: the use of referrals to construct a Distributed Directory Service
> is extremely clumsy and not well supported by common clients. If an

Very true...

> existing installation has already been built using referrals, the use of
> the chain overlay to hide the referrals will greatly improve the
> usability of the Directory system. A better approach would be to use
> explicitly defined local and proxy databases in subordinate
> configurations to provide a seamless view of the Distributed Directory.

> The use of 1 single proxy cache server seams to 'ease the pain' a bit,
> but does not seam like a very scalable approach. The use of
> proxy-overlays would make the server the client connects to function as
> a kind of non caching proxy, and in general 'be involved' in all of the
> requests, which again doesn't seam very desirable, and very
> single-point-of-failure.

As your proxy server will not hold any databases there is no reason why
you cannot have many copies of it. They can all be identical. You can
equip them with caches if you want to, or just set them up to pass the
queries through to the appropriate backend server. This removes the
single point of failure, and (with caches) improves the overall
throughput of the system.

Andrew
-- 
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|                 From Andrew Findlay, Skills 1st Ltd                 |
| Consultant in large-scale systems, networks, and directory services |
|     http://www.skills-1st.co.uk/                +44 1628 782565     |
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