I figure out that some logs from my ASA are missing in my syslog server. I do not success to find out why but for example, when I do an ASDM or SSH connection, authentication messsage does not appears each time in logs.
I observe that log messages are displayed every 4 second (I got 10 or more messages, then nothing during 4 sec and messages appears again). There is high volume on trafic on this ASA and I should have continuous logs on my SYSLOG & ASDM.
I check on another device in my lab with almost no trafic and I get several logs every second ! Pretty sure that a lot of the log are missing but I don't have any idea why. I check on Cisco Bug Toolkit but nothing relevant.