SMB Multi Channel implementation...... Not as Easy as I hoped.....

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SMB Multi Channel implementation...... Not as Easy as I hoped.....

DS920+ DS215J,
  1. RT2600ac
  2. MR2200ac
Operating system
  1. Windows
Mobile operating system
  1. Android
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What I thought would be an easy upgrade to increase transfer speed of my 920+ from my PC using the new SMB Multi-Channel so far is not working for me.

As I only had a single ethernet port on my Asus Motherboard, and there was some warning that suggested that each of the two ports on in my case a PC (Win10) should be identically rated … I opted to add a 2 Port PCI Express Card. (Dual-Port PCIe Gigabit Network Card 1000M PCI Express Ethernet Adapter with Intel 82575/82576 Two Ports LAN NIC Card for Support PXE for Windows)… Installed the Drivers and ticked SMB Multi-Channel.

The Diagram shown in Synology’s Knowledge Base was basic in that it shows 2 Cables from the NAS to the Switch and 2 Cables from the PC to the Switch. All 4 Cables connect to my LinkSys TL-SG1008D TP-Link 8 Port Gigabit Ethernet Network Switch …….

I benchmarked everything before starting using SpeedTest Tracker…. Following Marius Hosting’s steps, I installed the Docker Container and program. I thought I would be seeing Transfer Speeds between my PC and the 920+, but it appears its only charting my Internet up & Download Speeds.
321 Bytes s.jpg

Using the Network Resource Monitor in DSM, I do show LAN 1 & 2 operational, but with 275kb/s Download.

Not certain as to its usefulness or accuracy, but when I did an incremental Backup in Reflect, it claims a Transfer Rate (PC to NAS) of 1.5 Gb/s

Suggestions are welcome…. Hopefully I’m missing something simple….
-- post merged: --

conn diagram.jpg
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Watching thread because My Supermicro Server (W7-64) has dual GB Ethernet, and one of them is not being used right now.....
Maybe not... W7 only supports SMB 2.1 per MS.
And not clear if the SM server embedded Intel Dual Ethernet supports current RSS, so I'm officially Out! But might help others..
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That's the hw connectivity done. Have you activated smb multichannel on the NAS side? Are your LAN adapters separated but in the same subnet (no LAG)? How are you connecting from your client to the NAS exactly (protocol, port, etc)
Thanks Rusty for replying..... Turning on SMB Multi Channel in 7.2 was the easiest part to accomplish.... regarding your question of "connections... I am using an Unmanaged Switch.... and all 4 Connections are made there. And the LAN Adapter is on a single Card on the PC. It sounds like a Managed Switch is required to implement SMB Multi in this Setup from your questions.


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Update..... Just received an updated Intel Adapter Utility & Driver Set from the Card supplier. The Hardware comes back as "All OK", but claims none of the cabling is connected or passes any tests. Cables were all tested and working and of course I have always had full access to the NAS so I'm a bit dubious on the Cable Test utility results.


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I echo what @Rusty has asked for as SMB MC can be a bit fickle.

Can I make it work - yes - but it comes with caveats and potential tweaks needed or, in come cases, just a frustrating no.

The good side - SMB3 MC to and from my single Win10 server to my RS819 (technically not supported by DSM but that is just Synology doing market segmentation):

20230708-Think to Gimli-SMB Multichannel-CDM.png

20230708-Think to Gimli-SMB Multichannel.png

Aside from the config changes, to get this to work I needed 1 static and 1 dhcp reservation on the NAS, changing the interface priorities on Windows, clearing all the switch settings, Windows only, religious chanting and even 9k frames contributed to the positive outcome.

Meanwhile, macOS = no, DSM to DSM = no (go figure that one!), slightest change from the working config = no. However, I did have no issue using 10 GbE NICs to the switch and 2 x 1GbE links to the NAS. Others have had issues with that but for me it has proven to be no issue at all.

So no, not as easy as I hoped...

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Robbie...... Your explanation makes sense... most of all the chanting. I believed I could pull it off, and it was only NIC I needed.

It was worth a shot, but it's now apparent its a bit more involved than ticking the SMB Box in 7.2 and throwing on some cables.
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Still, for those without multi gig PCIe cards in their NAS the multichannel tuning is worth the effort. Especially with Synology releasing 2024 products trapped behind stupid 1 GbE ports. Madness really - even a single large-capacity HDD is handicapped by the interface speed.

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Robbie.... I came up with a few possible simple changes to continue my attempts. I'm not confident with the Speed Tracker App I'm now using.. the numbers just don't make sense to me.
May I ask what method you use to chart Rx/Tx to your NAS? The Read/Write (with green progress bar) shown in your Screen grab is not something I've found. I'd like to try yours to see.....
I'm just waiting for a another matching cable so both will be identical, and will also move the 4 cables from the Switch to the RT2600 to see if there is any different thruput.
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It's a good question but (as you probably already expect) not one with a clear answer due to all the elements that are in play during testing.

The simple Rx/Tx throughput I screen grabbed was taken from Crystal Disk Mark (PC) to a mounted folder on the NAS. It is a simplistic test but as you can tune it you can force it to saturate the link even on a NAS with a very slow processor. The macOS equivalent is Amorphous Disk Mark.

I test to/from my primary NAS with an instance of Open Speed Tester installed on the NAS. I highly recommend it for quick checks of LAN and connectivity health but it does not run that well on NASes with rubbish CPUs (eg my RS819 & RS217) so I didn't run it for the above example. It works just like an internet speed tester, so a very familiar format.

For diving into stuff with more detail then iPerf3 remains the weapon of choice. More complicated I guess but it does exactly what you ask it to do and demands very little from even a weak CPU.

Sorry there isn't a 'perfect' choice that covers everything (especially when testing IOPs, different protocols, multiple users etc) but that is probably the reason you haven't found one!

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Appreciate your always quick replies!

Selecting a method to show throughput numbers each has challenges.... and I now wonder why Synology has not provided this as a GUI in DSM. Maybe this is not info most want to know, and they sure make it challenging to extract it.

I'll try Open Speed Test.... I've found some step x steps....
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Thx's for the suggestions... I changed to Open Speed Test installed via this method I followed:
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So my benchmarked numbers (before SMB Multi) is supposedly measuring (with no load) between the NAS and PC.

I awaiting the new cables... we'll see if it changes anything.

NAS Speed before SMB Multi 7.11am 7.9.23.jpg
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Have stayed quiet on this thread because I'm sure my results aren't that representative

I have quad 1 GbE on the DS1520+ with the first three ports in dynamic LACP LAG and the fourth standalone. The IP addresses are manually configured (though reserved in DHCP to avoid assignment) and on the same LAN subnet. The SMB multichannel is enabled. The NAS is plugged into a 24x 1 GbE managed switch. This switch is uplinked/LAG’ed to a multi-gig managed switch.

On my Mac Mini there is a built-in 10 GbE and two Apple adapters providing Thunderbolt 3-to-2 the Thunderbolt to 1 GbE. The 10 GbE is connected to the multi-gig switch 10 GbE port, and the 1 GbE is connected to the 24x1 switch. I’ve configured nsmb.conf to prefer wired, and I have confirmed that multi-channel doesn’t work with wireless+wired. But it does work for my combined 10+1 GbE interfaces. It does not work single 10 GbE to multiple 1 GbE.

A rough ‘n’ ready Black Magic test to a shared folder on a Basic volume gives this for the 1GB test. The results vary and can be lower at 130-140 MB/s.


Though this isn’t that great when considering the Mac Mini’s internal storage :)

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Frebert.... you've assisted me in the past, so your thoughts are always welcome. I'm not well versed in Network architecture use and do my best following others instructions and advice. Just trying to make sense of the numbers, though I just wish in this case to be sure the tx/rx #'s are actually representing throughput from the PC uploading to the NAS....
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No luck at all for me with 10 GbE macOS to multichannel DSM. I don't understand why though.

macOS to DSM via 10 GbE works just fine, even on your 'rough 'n' ready' test:

 2023-07-09 at 16.35.06.png

Not tried a macOS SSD test though.

Edit: macOS SSD test - reads are slower than writes apparently.

 2023-07-09 at 16.55.13.png

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I see your using BMG Speed Test... I installed it, set it at 5Gb and aimed it at a Mapped Drive on my NAS...... These numbers are not even close to the previous Open Speed Test results of 984/990 (non SMB Multi).... Maybe this result is the reason its not widely suggested as a NAS Speed Test...

Just trying to Bench Mark before I do testing with SMB....


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I wonder if mine works with the Mac’s 10 GbE port is because the multi-gig switch uses 4x1 GbE to LAG to the 24x1 GbE switch… that it’s in effect limited down to 1 Gbps by the inter-switch LAG. I only put the 10 GbE in the Mini’s spec so that it would be there when I upgraded other things, like the multi-gig having a spare SFP+ for a future NAS.

The speed tests types differ in how they do testing. The Black Magic test is quite simple in that you have to have the volume mounted, so mine is mounted using SMB, and it write/reads data to this target. iPerf3 isn’t doing disk write/read and doesn’t use a mounted file share as the transit service, it uses its own service to send and receive data between the client and server… so it will only be using one LAN interface.
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