On Samba 3.6.x we regularly increased the log level on the fly using the 'smbcontrol smbd debug N', and it generally gave the same output in the log.smbd file. However, when running the same command on 4.1.x I've found that it does not quite seem to match the behavior of 3.6. Far fewer log lines end up in the log.

Capturing logging during a fairly simple 'ls' operation with smbclient shows that the number of log lines captured are fairly similar on 3.6 but very different on 4.1.

[3.6]$ wc -l *txt
  1787 3622log_sample_config0+smbcontrol9.txt
  1789 3622log_sample_config9.txt

[4.1]$ wc -l *txt
   454 4111log_sample_config0+smbcontrol9.txt
  3161 4111log_sample_config9.txt

I created the files with the following script:

###############
SHARE=g1
service smb stop
echo > /var/log/samba/log.smbd
service smb start
sleep 1

LL=$(grep 'log level' /etc/samba/smb.conf |cut -d= -f2 |sed 's/ //')
SUFFIX="config$LL"

if [ "$SMB_CONTROL" = 1 ]; then
    echo "using smbcontrol"
    SUFFIX="$SUFFIX+smbcontrol9"
    smbcontrol smbd debug 9
fi

tail -F /var/log/samba/log.smbd > log_sample_${SUFFIX}.txt &
echo ls | smbclient -U 'engwin2k8\johnm%Xxxxxxx1' //localhost/$SHARE
sleep 1
kill %1
##################

Our Samba build is an rpm we compile from sources. I am attaching the log samples I mentioned above to the bug. I decided this was worth a bug because the results are so radically different on the two versions. It was extremely handy to use smbcontrol to change the log level in the field, and so if this was intentional I'd like to humbly ask for the old behavior again. :-)

If there's any other information I can provide please let me know. I have not checked to see if winbind behaves similarly, as I haven't needed to increase the logging on that server as often.