Re: Release new code: - API

To: Mark <mark@xxxxxxxxxxxx>
Subject: Re: Release new code: - API
Cc: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
From: Julian Anastasov <ja@xxxxxx>
Date: Sat, 28 Oct 2000 15:06:50 +0000 (GMT)

On Sat, 28 Oct 2000, Mark wrote:

> > What is the exact scenario for this trick.
> My server knows the ideal real server to connect a client to after the first
> time it connects. If the director re-connects the client to the specified
> real server next time, locking between real servers is reduced to zero (my
> caches are read/write). This is outlined further in a message i posted on
> October 20 called "API Idea"

        You want the client to reconnect again after the director is
informed for the redirect? This will break the rule that each persistent
connection has the same destination (real server) as the connection
template - the first connection still remains linked to the first real
server even after the redirect. Currently, may be this is not a problem
because after the connection creation (the scheduling) the template is
not referenced from the connection but I'm not sure for the future.

        The connections don't timeout immediately, i.e. the transports
have some requirements in this direction, the TCP TIME_WAIT for example.

        But I agree that such feature is useful - the ability to create
this kind of affinity. But there are implementation issues we must
resolve for this to work.

        Currently, the services have persistent network mask, so this
redirect will move all clients from the same network (oh, yes, may be
you are using the default /32 mask) if we are going to play with the
connection template.

        So, we have to clear this idea, the well defined features
will not create problems later.

        And I of course don't know your case and whether there are other
solutions for your problem. Only you are sure that this feature
is the only solution :) Some LVS forwarding methods allow you to
redirect to real servers, i.e. ignoring the director. This is possible
when the real servers are available directly to the clients. For web
this can look in this way: redirect from www to www1. I don't know
what can be the effect after all these redirects. May be you are going
to double the number of requests? And there are cases that such
features are very well handled using L7 switches.

        So, are there any other users with similar needs? We can
try to clear this idea to work for all.

> Mark Pentland


Julian Anastasov <ja@xxxxxx>

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