[olug] Border management / server farms

[Christopher Cashell]

At Wed, 04 Feb 04, Unidentified Flying Banana Jay Hannah, said:
> Anyone have any experience high availability web/database farms?
> 
> I want to have X web servers and Y databases. I need some magical 
> device that can know when server(s) in the farm(s) are offline, happily 
> continuing to route requests to the other server(s) that are online.

I've heard of a couple of things that might, at least in part, do what
you're looking for. . . but some of them would depend on some specifics
of your application.

Are you looking for a generic solution for use with an existing
application?  Or do you have the ability to customize/develop the
application with high-availability in mind?

If the application is not yet finished, or not yet started, you might
want to look into using an "application server" as the framework for
your project.  Many of them natively support database pooling, and could
greatly simplify things for you.

> Preferrably I'd use some slice of Linux magic. Alternately, I could 
> spend $10K or whatever on some device from Cisco. This is all 
> hypothetical at this point, looking at options.

You also need to figure out exactly what kind of setup you're looking
for. . . specifically, are you looking for just a database pooling
product, or also a web server pooling product?

A database server pool will generally be highly dependent on the
platform, language, and other specifics of your application.

> I'm just looking for ballpark info (product names) from anyone w/ any 
> experience.
> 
> (Yes, I know I could load multiple DNS entries, but I don't want to 
> have to wait for DNS timeout(s) if server(s) are offline.)

To distribute load among web servers, the 'traditional' method is to use
round-robin DNS entries.  If that's not acceptable, there are a number
of alternatives, ranging from setting a single "point of access" box
that uses NAT to distribute requests to a private pool of web servers,
at the simplest end, up to expensive commercial solutions.

> Thanks,

I'm by no means an expert here, and in all honesty I have little direct
experience with high-availability and load balancing.  Most of what I
know comes from involvement with projects that were dealing with these
problems, and I followed their progress out of curiosity.

I don't know that I can be of much help, but if you can provide some
more specifics about what you're doing, what sort of application and how
it's developed (platform, language, etc), I'd be happy to offer what
knowledge I have.

If I understand things correctly, though, I think you're looking for two
solutions, one for HTTP load balancing, and one for database pooling.

> j

-- 
| Christopher
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| A: No.                                         |
| Q: Should I include quotations after my reply? |
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