hard drive - What are the factors that control transfer rate of large files in a single machine?

08
2014-07
  • inquisitiveIdiot

    I understand the difference between SSD and Hard Drive for why SSD writes and retrieves much faster, but what other factors govern how fast files are transferred both locally on a single machine or from a USB drive to a computer's local drive? What are the effects of the processor and other system specs?

    • Answers
  • Big Chris

    It is mainly down to bus speeds and whether the ports you are transferring between are on the same controller.

    e.g. If you have two SATA disks connected to S1 and S2 and transfer a file between the two you will not get the full (up to) 6Gb/s because the controller has to switch between the two devices. Unlike copying between SATA and, say, USB 3.0.

    The transfer will go as fast as the slowest device involved in the transfer.

    USB versions also make a difference.

    Your question is very broad so you should do some of your own reading up...


    • 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.

  • Seasoned Advice (cooking)

    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.