[Samba] Performance Issues With Samba and RedHat 8.

[Ross McInnes (Systems)]

Appologies if this has been asked before, i have searched the archives and 
while there are some almost related issues, none really answer my 
question/problem.

Recently (about 4 months ago) we purchased a new Dell 2600 (2.0Ghz Xeon 
2GB Ram), Machine (single cpu) and migrated the data and system from rh 
6.2 to 8 on this new server. By migrate i mean Installed rh8 fresh and 
moved the user data and .conf's, cron etc.

All was well and fine until one afternoon we had a massive slow down in 
the "system" (overall system, network etc. not this actual server). upon 
investigation we noticed that smbd was pulling 99% cpu time for about 
15-20 mins (before we decided to restart smbd)

restarting smbd, we had a small issue where all the old links etc tryed to 
contact the server so a little slow for a few mins then everything went 
back to normal. Very odd and certainly something we had not previously 
experienced on our older server.

so we kept an eye on it for a few weeks and all seemed well. we had a few 
reports of the system being incredibly slow at times, although this did 
not coincide with smbd using 99% cpu. using IPtraf/ethereal/ping showed 
that there wasnt a network issue to or from the server. 

Looking at the samba log file we started to notice a lot more OPLOCK 
requests/bad/failures etc around about the same time everything was going 
slow. So on a few of the shares we made them read only and put on FAKE 
OPLOCKS (netlogon, start menus etc). And we changed level2 oplocks to no. 

 # Turn off level 2 oplocks
        level2 oplocks = no

This seemed to improve things until it went slow/99% usage once again. 
(about 2 week or so later) Hair ripping time once again.

So after more research I read an article about the smbd.conf and some 
sort of windowing problem with samba and windows clients. so i modified 
"socket options" to be....

# Most people will find that this option gives better performance.
  # See speed.txt and the manual pages for details
  # You may want to add the following on a Linux system:
  #         SO_RCVBUF=8192 SO_SNDBUF=8192
socket options = TCP_NODELAY IPTOS_LOWDELAY SO_SNDBUF=8192 SO_RCVBUF=8192

Now this seemed to work and all was well until the past 3 weeks, where we 
have had to restart the server twice (no console response) and have had 
numerous problems with 99% cpu on smbd or this incredible slowdown of 
loging on, opening files, listing dir's etc.

Other details about samba is that its version 2.2.7a (according to 
smbstatus), we have nt4 clients and on average have about 100-150 users 
at peak times. it also has the wins server option enabled (so that it acts 
like a wins server)

I have no other ideas to try or even think to search for, so any advise, 
questions and maybe answers would be gratefully received.

Faithfully

Ross McInnes