Therefore, even you load all of the USB ports on your computer, the computer just switches the process between them very quickly.įor example, you drag-and-drop files to 3 USBs on your computer, the resources will be equally allocated to this three USBs, which means more USB you copy, more time you need. One the cache filling up, the transfer speed will go down to match the physical writing speed.Ī computer with a single CPU core cannot multitask as it only executes a single thread at a time. Then the reason might because write cache is filling up. If the transfer speed starts fast but drops down after a few seconds or minutes. ‧Transfer speed start fast and then slow down
One of the common reasons is that the anti-virus program checks every file and it will eventually slow the speed down. However, while copying multiple USBs you'll encounter some annoying problems. Wikipedia has more info if you want to really get into it.Using a computer to copy USB is the most common, convenient, and non-cost way. Firewire is better with multiple devices and better at constant throughput. Connect disks via Firewire if you want the best disk performance or Esata for breakneck speeds. It could also help to remove all unused USB devices because USB is pants on the mac. The best way to get performance from USB drives is to connect directly to the Mac's USB ports. In reality USB runs a lot slower than it's potential speeds.Ĥ80Mb/s is USB2 11Mb/s is USB1. Select USB in the list, somewhere in that window will be all connected devices, find the disk and look at it's 'potential' speed value.
Many keyboards support USB 1 only so you get slow transfers if you are connecting via them, some hubs have the same limitation.Īpple system profiler will tell you info about USB devices, Select Apple menu > About this Mac…, then click the More Info… button in the dialog. You need to be sure of what type of port you are connecting to. USB has 2 speeds, known as USB 1.1 and USB 2.0. I currently run osx 10.5.6 but it also happened on all osx versions I have had on the machines since 10.4.9.Ĭould I have some options set on my Macs that are affecting the copy/paste speeds or might it be caused by something else? This has always happened so it's not a new development.
#USB STARTS COPY FAST BUT SLOWS DOWN PRO#
I notice that at work, where I have an older iMac not as powerful as my home Macs, the copy speeds there are generally much faster and more consistent.īoth computers at home have loads of memory and free disk space (Mac Pro 2.8 8-core 10 gb ram 4 large hard drives & MBP 4 gb ram 2,4 santa rosa processor, 80gb free on hard drive) and this happens with a variety of usb memory sticks. It's just that the file copy/paste speeds are quite different in a random sort of way. There is no discernible pattern or specific type of file that is faster or slower than others. Sometimes the file copy speed is very fast the first time I do it.
Sometimes when it starts to copy a file, the progress is very slow and I stop the process, then try again and the copy speed is very fast on the exact same file. The free space I mention takes into account all the space needed by the drive itself of course - I expect to get about 5500MBs on a 6GB drive, maybe a bit less. I have noticed that when I plug in the usb drives to any of the Macs and start to copy a file from it to the hard drive of the computers, the transfer speeds can vary greatly. In addition, the copying starts off very quickly and then suddenly slows down: seems unlikely it suddenly hits a 'critical' free space level.
#USB STARTS COPY FAST BUT SLOWS DOWN MOVIE#
I have a Mac Pro and a MBP and often copy and paste files of 50 to 500 mb (image files or quicktime movie files mostly) using a usb flash memory sticks.
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