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External hard transfer rate inconsistency

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August 8, 2009 4:35:44 PM

I have two external hard drives connected to my system via USB. One is a 250 Gb I/O Magic and the other a 80 Gb Western Digital. I use the 250 Gb to backup my profile and its always been smooth sailing with transfers rates between 20-25 Mbps and would generaly take about 30 minutes or so to backup nearly 50 Gb.

Recently I upgraded my computer. I added a HD4850 video card and upgraded the RAM from one brand to another. After these upgrades I decided that I wanted to reinstall the OS and reformat the 250 Gb external drive. So, I just right clicked in Windows Explorer, choose the NTFS full format option and waited patiently. After the format was complete I attempted to backup my profile and I noticed that the transfer rate seemed very inconsistent and much slower then before.

I then compared it with my other external hard drive. I transfered a 500 MB file in roughly 15 seconds on the 80 GB drive (which is what I expected from the 250 GB) and on the recently formated 250 Gb the same file was taking nearly 4-5 minutes with frequent pauses that would hold up other applications on my system. The file eventually transfered but not without all these new delays.

I checked to see if Write Caching was enabled on the 80 GB hard drive is it was not. It was not enabled on the 250 GB either so I would expect to see the same performance. The drivers that are being used are both the same.

I thought maybe the way it was formated was causing it mess up so I downloaded a low level format utility and then formated the allocation unit size to 64k as opposed to 4096. Didn't make a difference.

The drives are both plugged into USB 2.0 ports. The hard drive I'm transfering from is a 300 GB Sata with a 16 MB Cache at 7200 rpm connected to a 3 Gb/s port on the motherboard.

Could this problem be related to IRQ settings? If so, how do you 1) tell if there is some new IRQ port sharing incomptibility 2) adjust the settings to isolate each hard drive on its own IRQ?

Thanks for any input in this matter!!!
a c 415 G Storage
August 8, 2009 10:47:42 PM

You should probably look in Device Manager (My Computer -> right-click -> Manage -> Device Manager) to see if there are little yellow exclamation marks beside any of your USB ports or disk drives.
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a c 87 G Storage
August 9, 2009 12:58:27 AM

I've seen this type of issue before with internal drives.

In the case of slow read and/or write in internal drives you go into the Device Manager, right-click and remove the PATA/SATA controllers then reboot the computer and let it rediscover the controller then the hard drives. That worked in every case.

For USB drives, try removing the USB connection, reboot the computer then reattach the USB drives.

FYI, it seems the fastest SATA/PATA->USB chip bottlenecks speeds at 32MB/second for any hard drive. If you transfer a lot of smaller files like MP3 music the average speed is also lower than transferring large files. There's a graph of this but it's due to the mechanical seek times.

It does sound like the first issue I mentioned or a similar software glitch.
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August 9, 2009 4:22:36 PM

photonboy said:
I've seen this type of issue before with internal drives.

In the case of slow read and/or write in internal drives you go into the Device Manager, right-click and remove the PATA/SATA controllers then reboot the computer and let it rediscover the controller then the hard drives. That worked in every case.

For USB drives, try removing the USB connection, reboot the computer then reattach the USB drives.


I tried what you suggested with just the 250 Gb hard drive plugged into the computer and the same performance issue was noted.


Quote:
FYI, it seems the fastest SATA/PATA->USB chip bottlenecks speeds at 32MB/second for any hard drive. If you transfer a lot of smaller files like MP3 music the average speed is also lower than transferring large files. There's a graph of this but it's due to the mechanical seek times.


That's why I measured the speed against one large 500 MB file. The 80 Gb hard drive will transfer this file in approx. 15 seconds everytime. The 250 Gb drive putts around, transfers a lot in a sharp burst, then pauses, then continues again. Eventually the file gets transfered, but what should have taken 15 seconds ends up taking 3-4 minutes.

When I deleted the USB connection from the device manager I noticed that the 80 Gb hard drive had two designations in the USB list: USB Mass Storage Device & USB Composite Device. I thought this was odd because the 250 Gb drive was only listed as a USB Mass Storage Device.

This may explain why when I go to the Properties => Policies for the 250 Gb hard drive and I look under "Write caching and Safe Removal" that only 'Optimize for quick removal' and 'Optimize for performance' are options whereas the 80 Gb hard drive also has a designation for 'Enable write caching on the disk'. It's not checked but just the fact that it is an option leads me to believe that for some reason this other drive is not being recognized as a hard drive or a USB Composite device any longer.

So how to I get my computer to recognize a USB external hard drive as hard drive and not something along the lines of a jumpdrive and return its designation as a USB Composite device in the device manager?


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August 9, 2009 4:33:13 PM

sminlal said:
You should probably look in Device Manager (My Computer -> right-click -> Manage -> Device Manager) to see if there are little yellow exclamation marks beside any of your USB ports or disk drives.


That was the the first thing I did. The devices all appear to be working normally. Thanks.
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