Its all about your upload speed. Not only how fast your upload speed is rated at by your ISP but how fast the server you are uploading to will allow.
Even if you had 100mb/s upload speed to the net that translates to about 12MB/s (the difference between bits any bytes) for which any newer harddrive could easily exceed. Newer 7200rpm drives can do a 100MB/s + transfer rates for what its worth. Newer SSDs do 400+ MB/s