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I have two Western Digital 1TB external USB 2.0 hard drives. These drives are connected to a server running Windows XP. I stream video files from both drives on this server to a variety of settop boxes, including two WD TV Live units and one Apple TV. Occasionally the video I'm streaming will pause for some period of time, between 30 seconds and two minutes. Once this period expires, the video hurriedly catches up to its previous status, forcing me to rewind. This occurs with video streamed from either drive, with video streamed to any of the three settop boxes, regardless of whether the streaming occurs over 802.11n wireless or over gigabit wired ethernet. The only common factors are the server itself and the model of hard drive.

While the video is frozen, I can VNC into the server successfully, and execute most operations normally. However, while the video is frozen, I am unable to access the data on the drive being read. Any attempt to access the drive results in Windows Explorer not responding. When it begins to respond again, the video unfreezes, indicating a common cause.

I suspect the problem lies in my server. Does anyone have any suggestions as to why it would be behaving in this fashion? I have difficulty imagining a hardware problem that would lead to such behavior. Is there some software setting or driver which might prove relevant?

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what is your media server application? USB connections would not favor fast read times. Frozen video could come from your server not being able keep up. Depends on a lot things. Video quality, wired/wireless, disk read, multiple users accessing them – Logman Jan 8 '13 at 3:21
No media server for the WD TV boxes, they read straight off the shared drives. I wouldn't think it's a stutter due to the drive not being able to keep up. The drives can source multiple HD streams simultaneously without problems for hours without incident. – Stephen Collings Jan 8 '13 at 3:41
If your hdds are sound, then the problem is network or hdd read access. If you are doing all this wireless then I would lean it that way. You should give us info on your network. – Logman Jan 8 '13 at 5:02
Like I said, it happens over both wireless and wired gigabit. And my vnc connection keeps working, while the hard drive stops responding. Doesn't sound like network issues. – Stephen Collings Jan 8 '13 at 13:38

A disk access delay could occur if communications to the hard drive is spotty or there are errors on the disk surface. The driver or controller may be performing retries until the problem works itself out or a loss of data occurs.

There are several things you can check:

  1. Check the Windows System Event Log to see if there are any hard drive errors being logged.
  2. Check the drives for SMART errors. I'm not familiar with the best way to check this in XP, but you can take a look at this comparison of SMART tools as a starting point. Since both drives are the same model it's possible they could be from a bad batch and both starting to go bad at the same time. This happened to me a few years ago with four identical hard drives purchased together. All failed prematurely at the same time, with SMART error notifications on Linux providing a brief advance notice before data loss occurred.
  3. Check the data and power cables to make sure they are securely connected.
  4. Check the hard disk temperatures (available via SMART) to be sure the hard drives are not overheating.
  5. Are the drives powered by USB or are they externally powered? If powered by USB you could be at or near the power limit on the USB hub. Windows sometimes reports this via a balloon popup. If this is happening, plug the drives into USB ports that are not using the same internal USB hubs. You can check Device Manager and View by Connection to see which hubs each device is connected to.
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I should (and will) add, this occurs in a seemingly random fashion. It does not seem to be related to what file I am watching, or where in the file I am. I can go back to the same point and it will not occur again. The video will progress normally. Also, this problem has occurred since the drives were new, so it's not likely to be an age problem. I'll try those ideas! Thanks. – Stephen Collings Jan 8 '13 at 3:26
I added item 5 in case the problem is due to USB power overload. – cantfork Jan 8 '13 at 3:40
The drives are externally powered. – Stephen Collings Jan 8 '13 at 3:42

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