I'm using Samba on Debian 8.4 (Jessie) to share files with a small number of Windows & Mac users (~20 total, ~5 at a time at most) and I'm seeing abysmal performance on read and write: tested by copying large file to and from the share, average < 500 KB/s.
I tested the disk by running
dd if=/dev/zero of=/srv/temp.tmp ... and
dd if=/srv/temp.tmp of=/dev/null ... and the disk can get to 70~80 MB/s so that's probably not the bottleneck.
I tested network by running
iperf and even on the edge of the wifi I can get 4~5MB/s, in door it's ~10MB/s so I don't think it's network related either.
An interesting observation is that during my test (copying large file to/from the share) while running
iostat -d -p md0 1 shows that the disk is not active all the time, but rather only read/write 1 sec for every ~10 sec inactive. This is not the case during the test with
All the tests were performed when I was the only active user to rule out possible interferences. This is a fresh install of Debian with some other stuff (apache server, php, etc) and a default config of samba. The share config is as follow
[share] path = /srv force group = data read only = No create mask = 0660 force create mode = 0660 directory mask = 02770 force directory mode = 02770