windows 7 - Ethernet data transfer rates

30
2013-10
  • zm15

    I have a simple computer networking question.

    Gigabit connection, both computers have 500GB 7200rpm hard drives. One is core i7 860, and the other is Core 2 Duo 2.66Ghz. Both pretty fast computers.

    When I hook up my desktop and laptop that are both running windows 7, with a crossover ethernet cable for a direct connection, why does the transfer start around 70-90 MB/s and then level off at 30 MB/s. I know the hard drives can handle more than that.

    Why can't I get sustained high transfer rates?

    • Answers
  • pete

    Many factors can affect this.

    • Speed of the drive itself
    • Other programs accessing the drives at the same time
    • Where on the drive the data is located
    • Drive fragmentation
    • Number of files being transferred ( 1 huge file will go faster than 10000 tiny ones )
    • etc.

    I can peak just a bit above 100mb/s on mine but it usually slows down and goes between 40 - 80mb/s after that depending on which drives and going to/from. I'm going between Win7 and Ubuntu.

    On Windows7/Vista there's a built-in throttling mechanism.

    Because multimedia programs require more resources, the Windows networking stack implements a throttling mechanism to restrict the processing of non-multimedia network traffic to 10 packets per millisecond.

    The throttling will come into effect only when you are running multimedia programs that are time sensitive. However, this throttling mechanism can potentially cause a decrease in network performance during the active multimedia playback period. This decrease in performance is likely to occur only on high speed networks that are saturated to maximum capacity.

    There are many things you can try. Its debatable as to how much of a performance boost you'll get. You could try this: http://support.microsoft.com/kb/948066

    You can also see if enabling jumbo packets on both machines could help. Larger packets could help. This may or may not help.. Check out the link. http://www.codinghorror.com/blog/2009/03/the-promise-and-peril-of-jumbo-frames.html

  • Brian Knoblauch

    I'm not sure that those hard drives can sustain more than that...

  • bubu

    1000Mbps is the theoretical maximum speed of the gigabit ethernet. In actual usage there is overhead generated by the protocol. For example, FTP has much lower overhead than windows file sharing (SMB). In practice 30-40MB/s is pretty good numbers for windows file sharing.

    Test with ramdisk if you are not sure whether the harddisk is the bottleneck. 30MB/s also resembles the maximum speed of harddisk connected via a USB interface (which it doesn't sound like the case to me)


    • Related Question

    performance - What might limit data transfer rate to NAS?
  • Holgerwa

    I have two NAS (Buffalo Linkstation Pro, WD MyBook World), which are connected to 2 PCs with a Gigabit LAN connection. All devices are in "Gigabit mode", meaning all show that their connection speed is really 1 GBit. But the transfer rates to and from the NAS drives are very low, on average 5 MByte/sec, copying large files with several GByte in size.

    Looking at the spec of the Buffalo drive, it should do up to 30 MBytes/sec. Of course, this is probably a best case scenario, but I think more than what I have right now should be possible.

    Copying files between the two PCs is much faster, about 25 MBytes/sec.

    What could limit the data transfer? What can I do to increase it?


    • Related Answers
  • KaoFloppy

    The WD MyBook World is CPU-bound or disk-controller-bound. If you do an online search for the throughput of the first versions of MBW, you will find that 5MB/s is quite common. There is nothing you can do about this.

  • Darren Newton

    Do your NASs support Jumbo Frames? And does your router/switch support Jumbo Frames? Check if they do, and if so, switch them on.

  • jerryjvl

    I wouldn't worry too much about Jumbo Frames if the maximum possible speed is in the order of 30MB/s.

    First thing to check is that the NAS is not doing anything else (other transfers, other actions) at the same time, because home NASes typically have severely limited processor capacity.

    It also depends heavily of the source and target of the transfer... the slowest link in the chain sets the top speed... so if you move files between the two NASes, then the overall speed will be that of whichever is the slowest NAS.

    Most modern harddisks should be able to do 50-60MB/s easily, but... if you put an older 'spare' harddisk in one of your devices this could very well also be limiting the maximum speed.

    I would not imagine that the computer that is doing the transfer is likely to be the bottleneck, but if you bring up the process manager you can have a look at the CPU and network graphs and see if either of those is peaking at the time... it could easily be that the network port on your PC is maxed out with other traffic meaning that there is only 5MB/s left.

    Based on the 5MB/s I'd almost have assumed that maybe the port on the PC (the middleman) is a 100Mbit port, because that'd make sense... 100Mbit = approx 10MB/s, but since the PC might be copying from one NAS to another, that means half the bandwidth is available for each connection.

  • contact us

    Check your port duplex settings. Routers/Switches set to Auto often set the ports to Half duplex. Check the port settings on the PC, Router, and NAS to see fi they are all 1GB Full duplex.