kernel: looutput: mbuf allocation failed

Dave [Hawk-Systems] dave at
Wed Apr 30 17:15:31 PDT 2003

>> Recently had a box go dark for a few minutes...  pulled the
>following from the
>> logs shortly after the box revived itself.
>> 	/kernel: looutput: mbuf allocation failed
>> been a while since we have touched the kernel config for this server...  any
>> pointers as to what settings we should lookat or touch to prevent
>this nastiness
>> from occuring again?
>What does 'netstat -m' have to say?

nx1# netstat -m
1045/1856/6144 mbufs in use (current/peak/max):
        977 mbufs allocated to data
        68 mbufs allocated to packet headers
970/1536/1536 mbuf clusters in use (current/peak/max)
3536 Kbytes allocated to network (76% of mb_map in use)
27349 requests for memory denied
14 requests for memory delayed
0 calls to protocol drain routines

this after another such "crash"...  have to say the server is recovering
beautifully from them.

I am wondering if this is a massive DNS query from one of the other servers
since both our DNS servers appear to get his while one of the web servers is
pumping out data at 70mbps (captured with MRTG).  Am checking that server for
any scripts that may be spam gateways since disabling qmail on the
web server seems to stop the bursts and subsequent crashes.

>According to that, you may want to tweak the number of mbufs available
>via sysctl.  If you search the list archives you'll find many conversations
>about this.

again, the above is just after a burst/crash, though the server is a primary
dns/authentication and mail server.


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