Is there a way to find out if a network outage occurred from logs?

Question

I have a red hat server running an oracle database. I can see in oracles rdbms' alert logs that a network outage of some sort occurred.

ORA-16198: Timeout incurred on internal channel during remote archival
LGWR: Network asynch I/O wait error 16198 log 3 service 

I want to know if the server registered something similar. I'm looking for NIC failures or simply a disconnection from the switch.

Note that the outage was temporary. I can access the server through ssh and I can ping the database service and the server itself, so my only way to tell that something happened is from logs.

Where can I look for that?

Answer 1

Check your /var/log/messages log file. You could find something like:

Jan  6 00:00:21 tseenfoo kernel: [104970.689167] atl1c 0000:05:00.0: atl1c: eth0 NIC Link is Down
Jan  6 00:00:31 tseenfoo kernel: [104980.550289] atl1c 0000:05:00.0: atl1c: eth0 NIC Link is Up<1000 Mbps Full Duplex>

Note that those are network card kernel module messages so they are driver dependant. They can do not exist at all or can change according to the different module active on you server.

If you can, run a tail -F /var/log/messages and quickly unplug/replug the cable (to see if those events are logged).

Check the driver documentation, often drivers offer some kind of debug mode you can use to log future outages.