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Hi all,
In my LVS-NAT system (IPVS-1.0.9 + ldirectord), I have an Oracle server on
the inside (web-db1) that primarily services the two realservers within the
LVS. However, I also have a webserver (www1) on the VIP side of the network
whose apache processes make Oracle connections through to the Oracle server
on the inside of the LVS. To allow this, I have the Oracle listener service
(port 1521) as an LVS service, with persistence set to 25200 seconds (7 hours).
I'm noticing a couple of different types of connections from www1 to the
Oracle listener port on the VIP: one with a source port of 0, and one with
a random source port, like so (the VIP is 'learn'):
[root@lvs1 gwaugh]# ipvsadm -Lc
IPVS connection entries
pro expire state source virtual destination
TCP 419:41 NONE www1:0 learn:1521 web-db1:1521
TCP 01:38 TIME_WAIT www1:2509 learn:1521 web-db1:1521
TCP 01:43 TIME_WAIT www1:2560 learn:1521 web-db1:1521
Connections with a source port of 0 take on the persistence of 25200
seconds (as I have specified in ldirectord.cf), but connections out of a
non-zero source port take on a persistence of 15 minutes (900 seconds). I
see from
http://www.linuxvirtualserver.org/Joseph.Mack/HOWTO/LVS-HOWTO.persistent_connection.html
that:
* For LVS persistence, the client is recognised by its IP (CIP) or in
recent versions of ip_vs, by CIP:dst_port (i.e. by the CIP and the port
being forwarded by the LVS). If only the CIP is used to schedule
persistence, then the entries in the output of ipvsadm will be of the form
VIP:0 (i.e. with port=0), otherwise the output of ipvsadm will be of the
form VIP:port.
Can anyone tell me why I get both types of connections (source port 0 and
source port non-zero)? Perhaps the 'source port 0' connection is some sort
of 'master' connection, and the 'source port non-zero' connections are some
sort of 'slave' connections?
What I'm really wondering is if it is possible to effectively make the
persistence for this connection infinite? Perhaps I shouldn't use LVS to do
this, but should use iptables instead...?
The problem underlying all this is that some apache processes on www1 seem
to lose their Oracle connection over time, so any client hitting www1 who
happens to get serviced by an apache process that has lost its Oracle
connection gets Oracle connection errors all over the page. I see from
http://www.linuxvirtualserver.org/Joseph.Mack/HOWTO/LVS-HOWTO.services.single-port.html#tcpip_idle_timeout
that one can set TCP idle timeouts for connections with ipvsadm - perhaps
this is what I should be doing?
Any thoughts appreciated...
Thanks,
Guy.
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