[Samba] Small file performance

[John Gardeniers]

Hi All,

We are experiencing painfully slow performance when transferring many 
small files via Samba. We are currently running Samba 4.5.1, although 
based on my searches the version doesn't seem to make any difference and 
this is a long standing problem.

The servers, both the primary file server and the testbed, have dual 
bonded 10Gb NICs and the client network is 1Gb.

Using a test directory of about 6,700 files, totalling about 200MB, the 
speed starts off almost reasonable but quickly slows down, ending up at 
around 3.5MB per second, in either direction. Testing from both Windows 
and Linux clients shows no discernible difference. When using NFS, SFTP, 
rsync, etc. the transfer happens so fast that it's difficult to time. 
Large files also transfer quickly.

Based on my searches I've been playing around with a number of settings. 
The testbed right now has the following options added to the basic smb.conf:

         socket options = TCP_NODELAY IPTOS_LOWDELAY SO_RCVBUF=32768 
SO_SNDBUF=32768
         read raw = yes
         write raw = yes
         strict locking = no
         min receivefile size = 16384
         use sendfile = yes
         aio read size = 16384
         aio write size = 16384
         strict allocate = yes

None of these options have made even the slightest difference. Playing 
around with the numeric values has at times caused the performance to 
deteriorate but never improve on not using these parameters at all. 
Equally, some other settings being suggested as a solution in Google 
searches have made absolutely no difference.

Is there anything else I can try that might actually improve 
performance? Perhaps something I missed in my searches? Or is this just 
a Samba issue that looks like never going away?

regards,
John