Slow network transfers

Discussion in 'Windows 10' started by trasher255, Dec 28, 2015.

  1. trasher255

    trasher255 MDL Member

    Jul 26, 2009
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    I am struggling with this since Windows 7. Copying through the Explorer of a 1,5GB file starts at a reasonable speed, but drops down to 8MB/s after about 5 seconds. See attachment.

    I have a gigabit wired network existing of a PC with Realtek GBE nic, a Netgear WNDR 3700, a gigabit hub and a Windows 2012R2 server with Intel Pro nic.
    Copying from the server to the PC works consistently at 100MB/s.
    Internet speed is not affected while copying.
    What I tried sofar: all kind of settings on the Realtek nic. Removing hub. Replacing network cable. Resetting router. Updated Realtek drivers.

    Could someone please advise on how to exactly troubleshoot this behaviour step by step? Thanks.
     

    Attached Files:

  2. T-S

    T-S MDL Guru

    Dec 14, 2012
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    Start trying to exclude the hub then the router using temporarily each of them, try also replacing the cables (cat 5 cables may work reliably at 1GBps but you need at least cat 6 cables to be sure).

    Accorting to the the above tests then you can narrow the various fault sources.
     
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  3. jonlurker

    jonlurker MDL Novice

    Aug 8, 2015
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    Had same problem miserable speed to my NAS over the network ,What worked for me was this.

    1. Run Admin CMD and copy this line : netsh int tcp set global autotuninglevel=disable

    2. Start -> Control Panel -> Programs -> Turn Windows Features on or off -> Uncheck the box "Remote Differential Compression". Click, OK and then you MUST restart your computer.
     
  4. pisthai

    pisthai Imperfect Human

    Jul 29, 2009
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  5. janos666

    janos666 MDL Novice

    Feb 25, 2012
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    #5 janos666, Dec 28, 2015
    Last edited: Dec 28, 2015
    For the first look, it seems like the HDD on the server side is slow (*) and the OS (on either sides**) runs out of cache/buffer memory (***).

    * it might be slow at hardware level [might be due to SATA cable, SATA controller, magnetic disc surface, read/write head, or various other hardware/firmware fault/incompatibility/misconfiguration], or at the logical level (the file system, [especially the free space chunks in this case] might be severely fragmented [and thus the relatively slow mechanical heads have to jump randomly over the disc surface which is very slow compared to the true sequential write speeds]).

    ** caching/buffering can happen on both sides of the network which might trick you into thinking you are experiencing impossible/unsustainable speeds (not factually real end-to-end transfer, just temporal "anomaly" on the reported numbers). Thus, the starting speed might be "fake" and you network is slower than you think (which is, in this case is probably due to some other faults in cabling, or hub/switch//router level).

    *** The otherwise free portion of your system memory + a relatively tiny amount of hardware memory (on the HDD controller or might be also on the SATA/RAID controller)

    This can also be some kind of QoS problem (something deliberately throttles the speeds above certain thresholds in order to have free capacity for other possible tasks), although I don't see that happening without explicitly configuring such things.

    I am almost certain you do not have a Hub but rather a Switch. In case it's a hub and you connect more than 2 simultaneously active devices to it (with 2 cables, it's merely a mechanical connector) you should get rid of it and replace it with a duplex switch (which doesn't slow your network down with >=3 simultaneously connected and active devices). Or you should try to use a single cable instead of a hub which connects two smaller ones (it that's the case and you don't need it as a repeater due to long cable lengths).

    I assume your router acts as a simple switch between your local devices (LAN) and NAT happens between WAN (~internet) and LAN (rather than doing NAT between separated VLANs which can be pretty expensive for the small integrated CPU of your router). But you would probably know if you configured VLANs (unless you used some QuickSet/Wizard for a "Guest network" but that usually affects WLANs aka WiFi networks only, not the wired LAN).


    Most of the main Windows upgrades brought some improvements to the SMB protocol but you need to upgrade both sides to the same generation (in order to use the latest SMB version - which is automatically negotiated) and some of the performance related features require special hardware/firmware/driver support (like the "SMB Direct") but these will only matter if you run out of raw CPU power (DMA is supposed to offload the CPU which is a good thing but irrelevant in terms of peak performance as long as the raw CPU power is more than enough regardless).


    By the way, CAT6 is for 10Gbe (those NICs are still too expensive for home uses), CAT5e should be perfectly enough for 1Gbe (assuming we talk about Base-T and we keep the standard's requirements in mind). For short ranges, even simple CAT5 might suffice. CAT6 might help if you use really long cables (close to the maximum allowed limit) and/or in a really noisy environment (for example, you run several pairs of ~100m long cables next to several pairs of high voltage/wattage power lines or you operate a lot of electronic machines in the building where the cables run in the walls).
     
  6. trasher255

    trasher255 MDL Member

    Jul 26, 2009
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    Thanks for all the replies! Appreciate that!

    But.... As speed from server to PC is adequate (100MB/s+), why would there be any problem with:
    - cabling
    - hub
    - SMB?
     
  7. gAnDo

    gAnDo MDL Novice

    Feb 3, 2010
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    Is it really a hub? If so thats probably your problem... You need a switch.
     
  8. 100

    100 MDL Expert

    May 17, 2011
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    #9 100, Dec 28, 2015
    Last edited: Dec 28, 2015
    There probably isn't. The most likely issue has been mentioned by janos666 already.

    No. You'd have a hard time finding a gigabit hub.
     
  9. EFA11

    EFA11 Avatar Guru

    Oct 7, 2010
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    #10 EFA11, Dec 28, 2015
    Last edited: Dec 28, 2015
    they still make hubs for Ethernet? hehe

    ed- btw first thing I would also like to know is what type of network cable it is. Look on the sheath of the cable, it should be at least CAT5E as mentioned.

    -ed2

    if cat5 you can see you wont get ~1GB since it cannot accomplish that speed. Cat5E can.

    Cat5 -> 100MB to 300 feet
    Cat5e -> 1GB to 300 feet
    Cat6 -> 10g up to 100 feet
    Cat6a -> 10g up to 300 feet

    Cat7-> 100g etc etc.
     
  10. trasher255

    trasher255 MDL Member

    Jul 26, 2009
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    My cabling is mixed. The computers are about 20m apart. Most of it is cat 6, pieces between router and PC and hub and server is <1m cat 5e. Wiring is the same on all connectors: 568B.
    I may have a switch no hub, I don't know but at the moment there is only one computer connected to it: the server.

    I use the Explorer.exe to copy files.

    I tried this as mentioned by jonlurker "Run Admin CMD and copy this line : netsh int tcp set global autotuninglevel=disable". No improvement.

    I repeat there is no transfer speed problem whatsoever when copying files form the server to the PC, initiated from the PC.

    Is there any network inspection software out there that can show me what exactly is going on during transfers?
     
  11. T-S

    T-S MDL Guru

    Dec 14, 2012
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    I don't think so. anyway almost surely isn't that the problem.

    HUB v.s. Switch makes the difference on relatively complex networks with concurrent traffic from many machines, hardly that's OP's case.
     
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  12. LatinMcG

    LatinMcG Bios Borker

    Feb 27, 2011
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    wow talk about generic junk switch.. id blame this.. or driver autodetect speed issues.

    change speed in device manager for realtek to 1gb instead of auto as test.
     
  13. 100

    100 MDL Expert

    May 17, 2011
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    :doh:
    Autonegotation is mandatory for 1000BASE-T.

    OP: Pretty sure your issue isn't network-related.
     
  14. trasher255

    trasher255 MDL Member

    Jul 26, 2009
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    Removing this switch from the network does not cheange anything. See OP.
     
  15. trasher255

    trasher255 MDL Member

    Jul 26, 2009
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    So, how to troubleshoot?
     
  16. endbase

    endbase MDL Guru

    Aug 12, 2012
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    Very strange issue I have also an server 2012 R2 and an windows 10 main machine and I have never experienced this issue except that after I had put 2 SSD in my server the speed from my main rig to server went drasticly gone up.

    So maybe you have to consider that if your server is running and you have many processes running at that time the write speed from main machine to server will be low other way around it will be much faster as there onlly will be reading done on your disk's at server. this is only an guess offcourse ! Good luck in finding your answer :)
     
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  17. trasher255

    trasher255 MDL Member

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    #19 trasher255, Dec 29, 2015
    Last edited: Dec 29, 2015
    (OP)
    Reasonable argumentation! Thanks.
    I sure have a lot of things going on my server. Not only it is the AD, hosts 2 websites, but also includes the capture of an IP camerastream and saving the stream on motion detection. This takes quite a lot of CPU load (between 20 and 30%) continuously.

    Edit: I even forgot to tell that I have Microsoft Exchange running also on this server!
     
  18. pisthai

    pisthai Imperfect Human

    Jul 29, 2009
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    #20 pisthai, Dec 29, 2015
    Last edited: Dec 29, 2015
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