Failover Recovery
J Springer
js at jspringer.net
Thu Jan 19 17:29:28 UTC 2012
4.1.1-P1
I am working to recover a server in failover mode.
The DISCOVER is broadcast, the responsible server (#2 in this case, it's the
server coming back on-line after an outage) handles the OFFER.
The REQUEST is sent to both servers with the server-identifier of the server
providing the offer.
The ACKs are returned from both servers. However, the server not responsible
(#1) for the offer is sending its IP address as the server identifier even
though that is not the IP address in the request.
This causes the modem to continually request until is receives the correct data
in the ack, which only comes from the offering server, prior to receiving the
incorrect data in the ack from the other server.
The server identifier is not in the configuration files nor is it used in any
OMAPI calls.
Why would the [primary] server receive a server identifier with the IP of its
partner in the request but send its own IP in the ack? Is there another
configuration option that might change the data in this field?
Looking back through the logs (no captures) prior to server #2 taken down, I see
this behavior -- continual requests until the ack is sent from the offering
server first. The only difference between prior to the failure and after
failover recovery is then we saw maybe 60-120 seconds for the correct ack to get
sent first. After recovery, it was in the hour+ range.
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