[Samba] Large Delays in Samba Responses

[Jeremy Allison]

On Tue, Sep 15, 2020 at 09:35:30AM +1000, Matthew Jurgens via samba wrote:
> From time to time I get applications that use data on a Samba share locking
> up for long periods. Sometimes minutes.
> 
> I am using a Windows 10 client and Samba 4.12.5 on Fedora 32
> 
> smb.conf is pretty simple:
> 
> /[global]//
> //   log file = /var/log/samba/%m.log//
> //   writeable = yes//
> //   workgroup = HOME//
> //   hosts allow = 192.168.2.0/24 //
> //   security = user//
> //   passdb backend = tdbsam//
> //   unix extensions = no//
> //   load printers = no//
> //   wide links = yes//
> //   # trying disabling oplocks to see if that stops my hanging/delay
> problems//
> //   oplocks = no//
> //   socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=65536
> SO_SNDBUF=65536 SO_KEEPALIVE//
> //
> //   # needed for DDWRT routers//
> //   ntlm auth = yes/
> 
> with shares like:
> 
> /[minecraft]//
> //        path = /opt/msm//
> //        create mask = 0765//
> //        comment = Minecraft/
> 
> 
> Changing oplocks did not help.
> 
> I've done some packet captures and they all look similar to this one:
> 
> https://www.edcint.co.nz/tmp/samba_ss01.jpg
> 
> Here you can see long delays where nothing is happening on the network, and
> the server is not resource constrained. While this is happening applications
> that are trying to use files on the share lock up. In the screenshot shown,
> there was some operations on an "opencv" file which was not even open or
> being touched by the application that was hanging. In fact, it would have
> been days ago since I last used the file in a different application.
> 
> smbstatus at the time did not list this file at all.
> 
> I had this problem years ago and it just disappeared and it was fine for
> years, now it is back and don't know what it is.
> 
> Any ideas? Any troubleshooting steps I can take?

This is from a Windows client, yes ?

Do you, or have you ever had the Windows Microsoft provided NFS client
loaded on that client ?