Nejc Škoberne-2 wrote:
Hello,
I've been trying to solve this problem by myself for a long time now, but
no luck.
I run a few dozens of FreeBSD 5.3/5.4 machines, which serve as routers,
NAT boxes,
Apache, Postfix, OpenVPN, ... servers. Most of them are low-cost PC
machines since
they are usually deployed to SOHO environments and the loads are rather
low.
I am having problems with the No buffer space available error like this:
Jul 18 08:49:36 Router openvpn[661]: write UDPv4: No buffer space
available (code=55)
so this is obviously when OpenVPN tries to send UDP packets. And also like
this:
Jun 23 06:27:38 Router pdns[2182]: Unable to send a packet to our
recursing
backend: No buffer space available
when PowerDNS DNS server tries to do some recursive work. I have been
searching Google
for a solution and I found out that the error should appear when the mbuf
(or sfbuf?)
is full and that I can print the current buffer status with 'netstat
-m'.
Because the error would show up (and not only show up, but also block the
network
operability for that server) at random times, I set up the swatch daemon
on all those
servers, so that as soon as the error is logged in messages, I run this
command:
#!/usr/local/bin/bash
LOG=/var/log/swatch.log
datum=`date`
echo == $datum ===
sockstat $LOG
echo
$LOG
netstat -n -a $LOG
echo
$LOG
netstat -m $LOG
echo
$LOG
ps ax $LOG
echo
$LOG
Even though the log was growing as I assumed, I couldn't find anything
particulary
interesting, because the netstat -m command issued by swatch (at the
time of the
error) still shows something like this:
2 mbufs in use
1/17088 mbuf clusters in use (current/max)
0/6/4528 sfbufs in use (current/peak/max)
2 KBytes allocated to network
0 requests for sfbufs denied
0 requests for sfbufs delayed
1819 requests for I/O initiated by sendfile
7578 calls to protocol drain routines
I am not sure, but as I understand it, this means that the buffers are
quite OK.
What would be the proper way to debug this problem? This is happening on
machines
with various hardware, from good old Pentium I with 32 MB RAM up to P4
3GHz, 1GB RAM,
various network cards (mostly rtl8139), with ADSL or VDSL, although the
errors are
very rare at the VDSL boxes (where the upstream bandwidth is substantially
greater).
So, usually the errors appear but the users don't bother really, so it
looks like
the problems goes away sometimes (the connection is restored), but
sometimes reboot
is needed.
Thanks for your ideas.
P.S.: If the output of the script above could be helpful, let me know, I
can publish
it somewhere.
Cheers,
Nejc
Hello Nejc!
Have you managed to solve this? I've just been having the same issue - I've
set up multiple OpenVPN connections with TAP-device (FreeBSD-5.3 as server,
5.4 as client, multiple 4.x as clients etc.) and the server gives the same
error regularly - I can't restart the server, the error occures every 30
minutes or so.. Do you know what's the deal with these buffers?
My netstat -m shows:
520 mbufs in use
515/128000 mbuf clusters in use (current/max)
0/5/6656 sfbufs in use (current/peak/max)
1160 KBytes allocated to network
0 requests for sfbufs denied
0 requests for sfbufs delayed
0 requests for I/O initiated by sendfile
9814 calls to protocol drain routines
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