Showing results for 
Search instead for 
Did you mean: 

Maximum log buffer sizes

Eric Marshott

Syslog is great, but it is much easier in a pinch to see log messages right in console/buffer.


Is it safe practice to use the maximum log buffer size shown in Cisco IOS and IOS-XE?

 -3850 running 3.6.6 shows range of value for `logging buffered ` as 4,096-2,147,483,647 
Where is log buffer stored on the device?

 -i dont see any files in any of the filesystems that are the same size as my max-sized log buffer

If the log buffer gets too large, could it overload the management plane?

Much appreciated


15 Replies 15

Joseph W. Doherty
Hall of Fame Master Hall of Fame Master
Hall of Fame Master

I believe syslog and console buffer are both stored in RAM.  So, the only issue with increasing their size would be to limit the RAM available to other system needs.  Which, if the network device doesn't have a need for that RAM, shouldn't create any problem.

What I don't know is whether RAM is immediately set aside when configured for a specific size or whether it's allocated as needed.  (I suspect the latter.)

BTW, console output could cause high CPU usage.  I.e.:"

Possible Causes of High CPU Utilization Due to Interrupts

High CPU utilization on an interrupt level is primarily caused by packets handled on interrupt level. Interrupts are generated any time a character is output from the console or auxiliary ports of a router.

"  Don't know if this still holds, but if it does, it would be best to avoid doing console logging.

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: