Rate Limited SSH connections on Intel QNAP

[manguvigo]

Hi everyone,

I have two new QNAP NAS on same network, with a Gigabit switch, a Gigabit router and 1Gbps fiber to the internet.

One TS-453D (Intel) with 8GB and Kernel 4.14.24 (latest update) and 4x6TB Exos
One TS-431P3 (ARM) also with 8GB, and Kernel 4.28 (lastest update too) and 4x3TB WD RED


They both download from the same origin servers, download the same files and connect to the same networks.

The Intel one ALWAYS tops on 200Mbps download per stream on ssh transfers from external sources
If I do a SCP or Rsync from any linux server (or WinSCP from windows servers) to the Intel QNAP, I always get max 200Mbps for a single connection. If I do two simultaneous connections, I got 400Mbps, 4 x...800Mbps... you get the point.
Also connection are very stable at plain 200Mbps, so I guess throttling

I first suspected from the backup software (NAKIVO), but I factory reset the NAS and still getting the cap.
Also I suspected from network, cables, NAT, switch...
But the weird thing its that the other QNAP (ARM) on same network stuff and cables delivers full speed connection on same servers.

Also doing an SCP, or any other traffic from inside local network gives full speed on the Intel NAS... So I almost discard OpenSSH throttle, except if this can be done only on non local ips.

And on Browser station on the Intel doing a speed test I got 1Gbps on every test I do.

So I have two NAS, one Intel and one ARM, both on same network... One delivers almost 800Mbps on single SCP, but the Intel one only 200Mbps max.on external ssh transfers (scp, rsync, etc..)

The only differences I can find are processor architecture, ethernet internal devices (Intel has 2x2.5G Reatek and ARM has 1 x 1Gbps and 1 x 2,5G Annapurna ), and kernel version...
I tried changing cables, IPs, ports, enabling DMZ on both....

Always same result... Intel QNAP (TS-453D) seems factory throttled to 200Mbps on SSH connections, and I cannot find any info how to disable that.

Any ideas? I'm reviewing sysctl parameters of the Intel kernel and comparing with the ARM's one, but see no difference on the main network stuff...

Anybody with a Intel QNAP 2.5G on a Gbit or faster internet connection can do an external test to scp a big file?

Thanks a lot

[manguvigo]

Ok, I've found the problem:

I have found a config issue on default Intel QNAP TCP config (factory default):

Default Receive TCP Window on Intel QNAP = net.ipv4.tcp_rmem = "4096 1638400 1638400"
Default Receive TCP Window on ARM QNAP = net.ipv4.tcp_rmem="32768 87380 16777216"

As soon as I changed the value on the Intel to the values on the ARM, ssh data transfer went double and beyond
I tweaked them, and now I got 1Gbps transfers.

code:

Code: Select all

sysctl -w net.ipv4.tcp_rmem="131072 524288 16777216"

I also tweaked wmem thinking about uploads on restores:

Code: Select all

sysctl -w net.ipv4.tcp_wmem="131072 524288 16777216"

Just remember to include the above on autorun.sh to survive reboots (/etc/config/autorun.sh)


Also, I think it's active on default, but not a bad idea forcing autotuning:

Code: Select all

sysctl -w net.ipv4.tcp_window_scaling=1

I hope it's useful If anyone has the same issue

Thanks