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First, I would like to say thank you! The LVS software is quite impressive.
Second, I'm having a problem finding the best approach for load-balancing our
Oracle service. Specifically, I would have the persistence template created for
the initial Oracle authentication period and then expire out of existence
(allowing other connections from this IP address to be load-balanced). My
situation follows:
We have LVS functioning in front of two Oracle servers running 9iAS (web
interface through Apache). If I understand the progression, a typical client
connection proceeds as follows:
1. Client opens connection (1 connection, opened and immediately closed)
2. Server offers JInitiator (1-2 connections, opened and immediately closed)
3. Once client has confirmed the correct version, JInitiator launches a java
applet. This opens and closes 1 or 2 connections before "establishing" a
connection for login.
4. Client logins (1 connection opened and closed for each failed attempt).
5. Client established a permanent session (1 connection that remains open for
the duration of the session).
Overall, I'm seeing between 5 and 15 connections in less than 2 minutes for
each client to the load-balancer. Once they're logged in, they maintain an
established connection until they disconnect (oracle sends a "heart-beat" that
allow the connection to be refreshed every 15 minutes).
Here's the problem. If I chose "source hash" for our load-balancing algorithm,
it appears that some of our clients (using NAT/PAT behind a single IP address)
will only be directed to a single back-end server. This effectively eliminates
much of the usefulness of LVS.
If I chose "round-robin", the clients are not able to establish an Oracle
session. The Oracle Java applet does not like being bounced between back-end
servers during the authentication phase. As a work-around, we have turned on
persistence (30 minutes) for the round-robin algorithm. Also, to keep the
established sessions active with the 15 minute oracle heart-beat, we've
increased the TCP Idle timeout from 15 minutes to 16 minutes.
This initially appeared to resolve our problems. However, I now realize that
the persistent templates are "refreshed" every time there is activity on the
established connection. Is there a way to turn this off? This will allow us to
maintain persistence during the first 2 or 3 minutes of the session (while it
is needed). Once established, persistence can expire and allow subsequent
connections to be load balanced.
Thanks!
Tony
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