900 Mbps file transfers across LAN?

[interconnect]

Just wondering if anyone knows the answer to this observation I made today. I found that on my ASUS RT-AC68U (running Asuswrt-Merlin 380.59) I can transfer a file between my computer (Mac mini w/ aftermarket SSD) and my NAS (with traditional spinning hard drives) at ~900 Mbps across my LAN. I was copying from the NAS to my Mac mini. Both devices are connected to the router with Cat6 ethernet cable and my entire LAN is Cat6 infrastructure end to end. It only achieves this speed for a minute or so until dropping back to ~300-400 Mbps. How is this? The SSD is only capable of sequential writing at 440 Mbps. Is Mac OS X writing to RAM first to achieve high speeds and then reverting to writing directly to disk once the RAM is full?

 

[sfx2000]

One gets some RAM caching at first - 900mBit is right at the max edge, but the bits do need to go somewhere...

 

[interconnect]

So that is, for sure, what's happening? I've never heard of anything like that before. Just trying to figure out what's going on.

 

[thiggins]

To really see what is going on, you need to do a packet capture and analyze with WireShark or similar packet analyzer.

I can't speak to MacOS, but Windows file transfers using SMB have a lot going on under the hood (multiple threads, adaptive window sizes) to speed things up and adapt to the connection's bandwidth.

 

[sfx2000]

I can't speak to MacOS, but Windows file transfers using SMB have a lot going on under the hood (multiple threads, adaptive window sizes) to speed things up and adapt to the connection's bandwidth.

Pretty much same thing on Macs..

 

[kamina]

Macs do use smb3 by default, but I doubt most NAS devices can have a very robust smb3 with multiplexing implementation as it was just added about a month ago? Is there even an official smb3 release with multiplexing?

My mac and qnap give same results with smb2 and 3.


Sent from my iPhone using Tapatalk

 

[BFG9000]

The SSD is only capable of sequential writing at 440 Mbps.

What SSD is this that is slower than a ten year old hard disk? I suppose it's possible if connected via Firewire 800, but any internal SSD should be faster than 55MB/s even in the oldest Intel Mini from 2006 (3Gbps SATA-2). More than likely the dropoff is due to the NAS.

 

[yorgi]

Just wondering if anyone knows the answer to this observation I made today. I found that on my ASUS RT-AC68U (running Asuswrt-Merlin 380.59) I can transfer a file between my computer (Mac mini w/ aftermarket SSD) and my NAS (with traditional spinning hard drives) at ~900 Mbps across my LAN. I was copying from the NAS to my Mac mini. Both devices are connected to the router with Cat6 ethernet cable and my entire LAN is Cat6 infrastructure end to end. It only achieves this speed for a minute or so until dropping back to ~300-400 Mbps. How is this? The SSD is only capable of sequential writing at 440 Mbps. Is Mac OS X writing to RAM first to achieve high speeds and then reverting to writing directly to disk once the RAM is full?

I have a 87U and my speeds are no more then 40-50MB/s which is what you are getting. I don't think that these USB controllers where designed to work like computers which give you over 100MB/s for the price they charge and the features they give, I would think its normal.
I think they should use better faster CPU's because they are so cheep now. If they do that then we would have a better experience over all with these routers.

 

[BFG9000]

OP said NAS is connected via Cat6, not USB. But yes, NAS box may have no better CPU than a router!

 

[sfx2000]

Even a low end NAS box will likely be a better solution than a shared USB drive on a router - they typically have more options, and the setup for them is more focused on the storage side.

 

[sfx2000]

Again - 900Mbps isn't unusual for Gigabit Ethernet - see below - iperf3 output over TCP

$ iperf3 -c 192.168.1.20
Connecting to host 192.168.1.20, port 5201
[  4] local 192.168.1.100 port 53868 connected to 192.168.1.20 port 5201
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-1.00   sec   112 MBytes   943 Mbits/sec                 
[  4]   1.00-2.00   sec   112 MBytes   940 Mbits/sec                 
[  4]   2.00-3.00   sec   112 MBytes   941 Mbits/sec                 
[  4]   3.00-4.00   sec   111 MBytes   931 Mbits/sec                 
[  4]   4.00-5.00   sec   112 MBytes   941 Mbits/sec                 
[  4]   5.00-6.00   sec   112 MBytes   940 Mbits/sec                 
[  4]   6.00-7.00   sec   112 MBytes   940 Mbits/sec                 
[  4]   7.00-8.00   sec   112 MBytes   940 Mbits/sec                 
[  4]   8.00-9.00   sec   112 MBytes   940 Mbits/sec                 
[  4]   9.00-10.00  sec   112 MBytes   940 Mbits/sec                 
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth
[  4]   0.00-10.00  sec  1.09 GBytes   940 Mbits/sec                  sender
[  4]   0.00-10.00  sec  1.09 GBytes   939 Mbits/sec                  receiver