[Samba] Samba process throttled back?

Lang, Rich LangR at specsensors.com
Mon Jun 20 14:20:18 MDT 2011

Lang, Rich wrote:
> Hello,
> We are running Samba 3.0.33 on a 2-node Linux cluster running RedHat 5.6 ES.  Its primary application is to serve out a single network drive to support our business (out 350GB in size).  For several years, this solution has been running flawlessly.  File access was almost as fast as a local disk, so putting files on the server was never a problem.  Our clients are running mostly Windows XP Pro.  We have a few Windows 7 clients.
    Any difference in performance between the client types?

None whatsoever.

    Did the problems coincide with adding win7 machines to the network?

Nope.  Windows 7 didn't appear on the network until 8 months later.

    Any new software on the clients (antivirus, firewall...etc?)  Is something using up more memory on them?

No - we can rule out the clients, since this happens on every client we have, no matter how it is configured.

    on your sockets, I up the SO_RCVBUF and SO_SNDBUF to at least 65536 each (more won't help until full smb2 support is in samba)....

I can make this change and see what happens.

    Did you get any new windows servers on your network around the time of the problem?  I notice that you have your 'os level = 0', that means for things like name resolution, your smb server will have lowest
  priority -- even below a win98 client, as I understand it.

No new servers were added.  Our os level is low because the configuration file is for a BDC and only the PDC and BDC are part of this Samba-only domain - no Windows servers are a part of it.

    You mention you ran an 'strace -f' on smbd.   Have you looked at a
wireshark trace?  That would tell you more -- like when negotiating a TCP session, if your windows client keeps reducing the RCV buffer size that would have told you why the reads were getting smaller.  Maybe you are getting packet drops, or similar

Good idea.  I would expect to see indications of this activity over the wire.  I'll let you know ...

n       Reminds me,  do you have switches or hubs, what type of ethernet speed...I take it nothing in the hardward on the clients or the server has changed?

We run on all switches - Linksys and Dell.  We have 100MBPS to each desktop.

    You say you are using RH.  Has the SW remained static since installation and through this problem increase (I.e. an auto-update of SW might have changed some setting in the kernel, or some firewall might have been added, modified....etc...)...

This is a real possibility, although we've booted the servers up using a kernel image prior to the problem appearing and the problem remained.  Maybe I need to go back to a kernel module rev prior to the problem.

    Are the windows client's 'paging' more?   I.e. was there any change
in the VB script or the SW it's using such that now there could be a memory leak, thus increased paging?

No - nothing like that is happening on the client.

    Have you set/optimized your TCP/IP params on XP? (and what little
you can do on Win7...  which is less configurable than XP)....   Have
you added more clients (significant?)...

These are pretty stock XP systems.  The problem was so sudden (worked great for years, then slowed to a crawl) that it has to be associated with a change on the server or the client.

    On the Win clients...what SP are the XP clients running at?   Many
people complained when SP2 came out -- especially affected were network
applications.   SP3 has the best performance of the XP series (even
better than the original), while SP1 was slower than 'SP0' (original), and SP2 was slower still...

We're all running at Windows XP service pack 3.

    I don't have any specific theories...just asking for more data at this point, since there are so many possible variables...and just having the information out there would help anyone investigate the problem...

Good luck!....


Richard G. Lang
Sr. Software Engineer
LangR at specsensors.com<mailto:LangR at specsensors.com>
(330) 659-3312

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