Large disparity between download and upload SMB transfer speeds

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Faust
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Joined: Sat Apr 22, 2000 4:34 am
Location: Huntington Beach, CA

Large disparity between download and upload SMB transfer speeds

Post by Faust »

Hello!

Recently upgraded the LAN to >1GbE. Having a bizzarre disparity between transfers between my main system and the NAS (both connected through a switch with 10GbE links). I can elaborate on the network items if necessary.

At the moment, if I transfer a 20GB test file (7z compressed movies) through SMB/mapped drive I get ~8Gbps from PC to NAS, ~1Gbps from NAS to PC. I get the same result if I do the same in safe mode with networking.

I have a suspicion it has something to do with the onboard Intel NICs (gigabit) which I cannot disable at the BIOS level for some infuriating reason, interfering with the INtel 10GbE PCIe card. Well, technically it's a 10GbE SFP+ card w/LC OM3 module. My suspicion is not based on anything more than "all I can come up with".

SG analyzer report:

« SpeedGuide.net TCP Analyzer Results »
Tested on: 2024.01.06 17:41
IP address: 76.169.xxx.xx
Client OS/browser: Windows 10 (Firefox 121.0)

TCP options string: 020423000103030801010402
MSS: 8960
MTU: 9000
TCP Window: 262656 (not multiple of MSS)
RWIN Scaling: 8 bits (2^8=256)
Unscaled RWIN : 1026
Recommended RWINs: 53760, 107520, 215040, 430080, 860160
BDP limit (200ms): 1051 Mbps (105 Megabytes/s)
BDP limit (500ms): 420 Mbps (42 Megabytes/s)
MTU Discovery: ON
TTL: 112
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0)



Any ideas? Thank you!
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Philip
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Location: Jacksonville, Florida

Re: Large disparity between download and upload SMB transfer speeds

Post by Philip »

Is the NAS using Jumbo frames as well? What is the CPU utilization of the NAS when transferring out? I would try to rule out the NAS resources being the bottleneck. I would turn off any "Green Ethernet" power-saving options on both end, any "packet coalescing", any "offloads" that could consume resources, other than simple stuff like CRCs.
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Faust
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Location: Huntington Beach, CA

Re: Large disparity between download and upload SMB transfer speeds

Post by Faust »

Hi, Philip!

Yeah, Jumbo Frames is on on both ends. The NAS is pretty simplistic with regard to network settings so there aren't any Green Ethernet or power saving settings in in that regard. If I hoook up my laptop with a USB 2.5GbE adapter it just pegs at just under the line speed (~2.2Gbps) NAS->laptop. Not long after I got the LAN elements set up I started chasing the problem, eventually reinstalling windows. Results:

Normal Boot:
iperf3
- NAS->PC 651Mbps
- PC->NAS 3.15Gbps

SMB Share
- NAS->PC 950Mbps
- PC->NAS 6.3Gbps



Safe Mode w/networking:
iperf3
- NAS->PC 824Mbps
- PC->NAS 4.73Gbps

SMB Share
- NAS->PC 917Mbps
- PC->NAS 8.4Gbps



After Reinstall:
iperf3
- NAS->PC 2.72Gbps
- PC-NAS 4.73Gbps

SMB Share
- NAS->PC 3.1Gbps
- PC->NAS 8.3Gbps


Not long after the reinstall, and I don't know exactly when (as soon as I got network connectivity I ran the "after reinstall" tests), things went sideways again. The NAS itself at this point is capable of the 8Gbps+ with half the drive bays occupied (it's an Asustor FS6712X, for what it's worth). The CPU and memory usage doesn't show anything being stressed. I'm still not ruling out the onboard Intel NICs' drivers are throwing a wrench into the mix since the 10GbE NIC is also Intel. I ordered a different NIC (Broadcom chipset) which I should have tomorrow. I do have a copper 10GbE NIC that I started this whole thing out with (surprise, Intel also!), but that also gave inexplicable results. I was just hoping the driver contamination would show up in the MTU/etc. settings. I may still need to reinstall Windows and try installing items one at a time to see if I can pinpoint it.

Even though this computer is ~4 years old, I love it and it's still solid as hell other than this weird transfer speed issue.

I'll keep monkeying with it and and report bak to see if we can make sense if it.

Thank you for the help, bud!
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Faust
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Location: Huntington Beach, CA

Re: Large disparity between download and upload SMB transfer speeds

Post by Faust »

Well, I got the new NIC installed. Looks like the driver conflict was the issue. I feel like I should be smoking a cigarette or something. I did have another question, though. The NAS only has a few Jumbo Frames options, thei largest being 9000. The NIC has 9014 and 9614. Is best practive to set the frame size on network devices as close to similar as possible, or as large as possible?

Thank you Philip! (apologies, I should have reduced the image size before posting)

PC to NAS
Image

NAS to PC
Image
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Philip
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Re: Large disparity between download and upload SMB transfer speeds

Post by Philip »

I would set them as close as possible, i.e. ~9Kb.
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Faust
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Re: Large disparity between download and upload SMB transfer speeds

Post by Faust »

Roger that.

Thank you, Philip!
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