DSM7.2 Multichannel between DSM, Windows and macOS

[Robbie]

I've got a bit of a weird one with SMB Multichannel. I've used Multichannel on DSM pre the 7.2 update with the usual CLI changes and I have left them in place on the Rackstations that Synology omits from its ethereal list. The NAS I have on the approved list (RS1221+) has multichannel selected on the GUI but it only has a single 10 GbE link at present.

All my NASes signal that MC is on and working. As per usual macOS displays its unwillingness to embrace SMB MC, Windows just gets on but DSM to DSM seems to fail when once it worked just fine. This has regressed with DSM 7.2, at least for me.

An example from the resource monitor on my RS819:

First trace is to/from a Windows 10 server (10 GbE) showing full use of SMB MC. Second trace is the ever-truculent macOS (10 GbE) just passing traffic on a single LAN link, again. Third trace is a DSM to DSM data transfer (happens to be HB in this case) just sticking to a single interface. On DSM7.1 SMB multichannel between NASes worked fine.

Anyone else run into the DSM7.2 to DSM7.2 multichannel weirdness?

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[Rusty]

Anyone else run into the DSM7.2 to DSM7.2 multichannel weirdness?

Confirmed it doesn't work when enabling the "official" option. I tested this back with the beta version of the SMB package when it arrived months ago, and the File Station mount from one NAS to the other didn't work. The official ticket also confirmed that and said that FS does not support it atm.

Also, 819 is not on the approved support list for MC based on the limitation section inside the SMB release notes.

Limitation

1. Please note that currently the SMB3 Multichannel function only supports x86 platforms. For models in x86 platforms, please refer to all models listed in this article.

Release Notes for SMB Service | Synology Inc.

Release Notes for SMB Service | Synology Inc.

www.synology.com

On the macOS, this should work (for the Intel-based one), but again, considering the notes, Apple SOC ones won't work (and does not work for me). Still, 10G to 10G transfer with no multi-channel (mac to nas) does work, but that's expected.

 

[Robbie]

Also, 819 is not on the approved support list for MC based on the limitation section inside the SMB release notes.

Limitation

1. Please note that currently the SMB3 Multichannel function only supports x86 platforms. For models in x86 platforms, please refer to all models listed in this article.

Just a Synology choice rather than a real limit and, as said, I've been running SMB MC on this RS819 in this config for quite a while. Presumably they are applying more market segmentation in the GUI rather than actual capability. Of course, Synology didn't make Samba either!

One thing I didn't try was unofficial DSM MC to another unofficial DSM MC. I'll give that a go when I get chance. I also noticed that the official version of DSM MC does not have the normal config files you usually see for SMB MC. It still advertises multichannel in the same way though:

rob@MBP-Rob ~ % sudo smbutil multichannel -a
Session: /Volumes/Video
Info: Setup Time: 2023-05-25 18:48:23, Multichannel ON: yes, Reconnect Count: 0

All my networked Macs are ASi rather than Intel so I have got used to Macs now being awkward with MC. Running them all at 10 GbE though, so hardly a bottleneck on my network.

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[Rusty]

Just a Synology choice rather than a real limit and, as said, I've been running SMB MC on this RS819 in this config for quite a while. Presumably they are applying more market segmentation in the GUI rather than actual capability. Of course, Synology didn't make Samba either!

All true

 

[Obioban]

Just a Synology choice rather than a real limit and, as said, I've been running SMB MC on this RS819 in this config for quite a while. Presumably they are applying more market segmentation in the GUI rather than actual capability. Of course, Synology didn't make Samba either!

One thing I didn't try was unofficial DSM MC to another unofficial DSM MC. I'll give that a go when I get chance. I also noticed that the official version of DSM MC does not have the normal config files you usually see for SMB MC. It still advertises multichannel in the same way though:

rob@MBP-Rob ~ % sudo smbutil multichannel -a
Session: /Volumes/Video
Info: Setup Time: 2023-05-25 18:48:23, Multichannel ON: yes, Reconnect Count: 0

All my networked Macs are ASi rather than Intel so I have got used to Macs now being awkward with MC. Running them all at 10 GbE though, so hardly a bottleneck on my network.

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So, as someone hoping to using SMB Multichannel on my RS819 to Mac Mini..
... how did you enable it, when not officially supported?

Also, any thoughts on how to force the Mac to do it? My hope is to use the built in 1G ethernet port plus a USB to 1G Ethernet dongle, to get 2G total between the NAS and Mini.

 

[Robbie]

So, as someone hoping to using SMB Multichannel on my RS819 to Mac Mini..
... how did you enable it, when not officially supported?

Nothing special to do it. The missing GUI setting does nothing more than write the additional options into the smb.conf file. You can edit this file yourself with a text editor using VI, VIM or whatever.

My file looks like this:

Rob@Gimli:~$ cat /etc/samba/smb.conf
# Copyright (c) 2000-2019 Synology Inc. All rights reserved.
#
# IMPORTANT: Synology will not provide technical support for any issues
#            caused by unauthorized modification to the configuration.

[global]
    printcap name=cups
    winbind enum groups=yes
    include=/var/tmp/nginx/smb.netbios.aliases.conf
    server multi channel support=yes
    aio read size=1
    min protocol=SMB2_10
    security=user
    local master=no
    realm=*
    passdb backend=smbpasswd
    printing=cups
    max protocol=SMB3
    winbind enum users=yes
    load printers=yes
    aio write size=1
    workgroup=WORKGROUP
Rob@Gimli:~$

The added lines are:

server multi channel support=yes aio read size=1 aio write size = 1

The conf file is only read at launch, so for them to be applied you can either reboot or type this simple command to restart just the SMB service:

:~$ sudo synosystemctl restart pkg-synosamba-smbd.service

You can also experiment with the aio read size between 0 or 1. It may not even matter these days.

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