Quick question RE: logs written to console...

[jmaxwellUSAF]

Cisco literature...

"The logging buffered command copies log messages to an internal buffer instead of writing them to the console."

When "writing [log messages] to the console", I would expect the logs to quickly fill up the memory. 

Questions:

1. where are these messaged saved (to flash?)?

2. are these console written logs ever erased?

Thank you.

[MHM Cisco World]

The R/SW save log in buffer memory when full the old log will erase and new log add to memory.

[jmaxwellUSAF]

Then what is the difference between "logging" and "logging buffered"?

[David Ruess]

The logging buffered should allow you to choose the size of the buffer to store logs before they are overwritten. The default size of the buffer is dependent on the make/model of the device and storage capability.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/esm/command/esm-cr-book/esm-cr-a1.html#wp4750306920

-David

[MHM Cisco World]

Logging <keyword > 

What is keyword with logging ?

[Joseph W. Doherty]

I recall just "logging" sends syslog messages to the console (which I also recall was [still?] not recommended for normal operations).  "Logging buffered" sends syslog messages to a RAM circular buffer (BTW contents lost if IOS restarted).  (The latter very handy when doing telnet like access to see recent syslog messages.)

[MHM Cisco World · Accepted solution]

first we enable logging 
then we config the logging buffer <<- this buffer is where the log is save, it different than real time log, real time can feed to console/VTY or server but also the log can save in RAM of R/SW for later check.
NOTE:- the size we can save the log message is small compare to syslog external server.

[Joseph W. Doherty · Accepted solution]

#1 Written to RAM.

#2 Yes and no.  The logging buffer is "permanent" (in the sense it depends on device's config).  Buffer management is "circular", i.e. when a logging entry is to be added, if insufficient space oldest entries removed to make sufficient space.

BTW, I recall older logging buffers could not be set larger than 64KB, but later might support multi GB.