Re: Reread of config without restart

From: Willy Tarreau <>
Date: Tue, 11 Mar 2008 21:36:04 +0100

On Tue, Mar 11, 2008 at 07:50:06PM +0100, Michael Rennt wrote:
> Willy Tarreau wrote:
> >On Tue, Mar 11, 2008 at 05:00:27PM +0100, Michael Rennt wrote:
> >>Hi,
> >>
> >>just tested it and it's working fine.
> >>
> >>Where is haproxy retaining the persistence database or is the old process
> >>actually handing over the persistence information to the new one in
> >>memory?
> >
> >no, and generally speaking, you should as most as possible avoid to
> >maintain
> >any state in any equipment. Persistence is the worst thing to maintain
> >because
> >(when it is possible), it costs a lot and is generally a sign of poor
> >initial
> >design.
> >
> >Simply insert a cookie for your persistence and have any process and/or any
> >machine be able to replace the first one at any time.
> But how is persistence solved with source based balancing for example? How
> is haproxy maintaining the mapping of source ip to the destination server?

There is no IP-based persistence. If you need to use IP address, you use address hashing. But generally this is not used since this is a poor and unefficient solution to apply persistence.

> Also, how is query hashing realized? Do you put the hash into a cookie?

No, the hash is computed everytime it is needed, and the result is used to select the server. But once again, hashing does not provide persistence. In fact, it's even an alternative which is often acceptable when persistence is not an option. In fact, I'm not sure I really understand your problem.

Willy Received on 2008/03/11 21:36

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