[Samba] No increased throughput with SMB Multichannel and two NICs

[Daniel Vogelbacher]

Hello,

I'm running Samba 4.4.5 with enabled SMB Multichannel. The Linux server
has two 1GBit/s NICs and for testing purposes I've shared a tmpfs
mountpoint with 2GiB and ~2GiB large test-file.

My Windows 10 host has one dual-port 1GBit/s NIC, and if both interfaces
are enabled, Get-SmbMultichannelConnection lists active multichannel
connections to my Linux SMB server.

If I disable one NIC on Windows, the other NIC is used with ~1GBit/s
when transferring the test-file from Linux to Windows.
If I enable both NICs, instead of 2x1Gbit/s I only get ~500MBit/s per
interface (but both interfaces are used).

So instead of doubling the throughput, traffic is split up between two
interface half by half.

Is it possible to change this behaviour?


Hardware infos on Linux:

07:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
Connection (rev 03)
08:00.0 Ethernet controller: Intel Corporation I210 Gigabit Network
Connection (rev 03)

# uname -a
Linux mz4 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-2+deb8u3
(2016-07-02) x86_64 GNU/Linux

/# /usr/local/samba/sbin/smbd --version
Version 4.4.5

Hardware infos on Windows 10:
Intel PRO/1000 PT Dual Port Server Adapter



Regards,
Daniel Vogelbacher