proxy module for load balancing?

[Michael Smith <mj...@cursci.co.uk>]

Hi all,

I was wondering if anyone has any thoughts on using the proxy module for
a form of load balancing.

I've already used ProxyPass to pass certain requests off to other
machines, which has helped share the load somewhat.

I was considering looking at being able to have more than one ProxyPass
directive for a given path, such that the server passes the requests in
a round-robin form - or possibly even according to load. If this were
possible it might save the heap load of money that Cisco's LocalDirector
costs, and provide better functionality in the process.

Does anyone have any thoughts (or patches :-) ?

Mike

Re: proxy module for load balancing?

[Dean Gaudet <dg...@arctic.org>]

The proxy doesn't appear to handle multiple A records right now... to work
properly it should cycle through A records when timeouts/RSTs occur. 

At any rate there are alternatives to LocalDirector.  Actually I'm testing
one right now, two of the 5 hotwired servers are sitting behind a
tcp-level packet rewriter <http://www.coyotepoint.com/>.  It's been up for
5 days without a problem.  There's another similar product at
<http://www.f5.com/product.html>.

You're right though, a lot of the same functionality can be had at the
application level, with increased latency and load (two extra memory
copies from kernel-space to user-space and back).  For reference, the
coyotepoint product above seems to be adding 300 microseconds of latency,
and I've got it running on a pentium 166.  It's barely even noticing 50 to
60 new connections per second. 

What is scary about both solutions is the single point of failure that
they introduce. 

Dean

On Tue, 18 Mar 1997, Michael Smith wrote:

> Hi all,
> 
> I was wondering if anyone has any thoughts on using the proxy module for
> a form of load balancing.
> 
> I've already used ProxyPass to pass certain requests off to other
> machines, which has helped share the load somewhat.
> 
> I was considering looking at being able to have more than one ProxyPass
> directive for a given path, such that the server passes the requests in
> a round-robin form - or possibly even according to load. If this were
> possible it might save the heap load of money that Cisco's LocalDirector
> costs, and provide better functionality in the process.
> 
> Does anyone have any thoughts (or patches :-) ?
> 
> Mike
>