Kernel panics involving mbufs (FreeBSD)

This document pertains to kernel panics with FreeBSD involving mbufs.

This is a well documented problem with programs such as ircu, and inn that involve a lot of clients, the solution is generally to set the option 'NMBCLUSTERS' to a reasonably higher number the default is 1024, you should first try increasing this *10 (10240) and continue checking mbuf usage with netstat -m.

It has been recommended that this be increased as far as *50 (51200) (although more won't hurt, it uses more memory, so don't go too far overboard) it's been stated over and over that the default is very low, but then, you're supposed to know how to configure your OS for what you're doing right? =)

There is a note in the configuration for this:

# Note that you will probably want to bump up NMBCLUSTERS a lot to use
options NMBCLUSTERS=1024
Merely change the 1024 to the number that best suites your system.

Contributions

• poptix poptix@poptix.net | April 17, 2000 Matthew S. Hallacy