I just upgraded my internal development VM running Ubuntu 11.10 with Samba 3.6 to Ubuntu 15.04 with Samba 4.1 (fresh install, new VM). Everything is working great, with the exception that my log tailer (BareTailPro) watching web development output is now refreshing very slowly.
Under Samba 3
Log writes server-side appear in BareTail near instantly (< 0.25s). Subsequent writes are also instant.
Under Samba 4
Log writes server-side appear in BareTail near instantly on the first write. Subsequent writes wait 10-12 sec before BareTail shows them. Samba logging set on level 3 shows reads happening the moment BareTail shows the update. It's as if BareTail is checking for a timestamp update (the software checks every 250ms) but is being told the old timestamp until 10-12 sec passes. When the update is fetched, no lines are missed.
I have recreated the VM with 14.04 and 15.04 on different physical machines. Internet searches return typical suggestions of setting socket options, but nothing has helped. I've actually found very little about log tailing over SMB, but it used to work great and now not so much. The combination of Windows 8.1 and Samba 4 appears to inject some sort of buffer on the file timestamp update across the network. Has anyone encountered this and know of a fix server-side or client-side?