USB 2.0 Transfer Speed Very Low

[mattlau]

So here's my problem:

For a particular machine running Windows Server 2008 x64, whenever I connect a USB 2.0 device and initiate a large transfer, the transfer rate starts very high (18 MB/sec) and rapidly slows to a crawl (< 1 MB/sec).

What's going on? How can I troubleshoot and resolve this?

Thanks.

 

[cdogg]

Troubleshoot it by doing the transfer to another location, such as an internal drive or network folder. See if the issue happens during that transfer as well.

It seems odd that this has anything to do with the USB interface. One thing to check though is the length of the USB cable. You shouldn't be daisy-chaining multiple cords together if you can avoid it. Stay under 15ft (I realize the max is higher).

Also to make sure it's not the USB device, connect it to another PC and try a similar transfer there.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
[tab][navy]For posting policies, click [/navy]here.

 

[mattlau]

This seems to be related to the number of files being transferred. If a single large file is copied, the transfer rate remains high. If multiple small files are transferred, the transfer rate plummets.

 

[victorv]

hi mattlau,

has been installed or activated items as:
- Indexing Service,
- performance counters ?

your last post suggests me these doubts.

ciao
vittorio

 

[cdogg]

This seems to be related to the number of files being transferred

mattlau,
I pretty much assumed that after your first post. What I am trying to say is that you need to find out if the problem is the PC or if it is the USB device. And if it is the PC, then you need to find out if it only has trouble transferring to the USB device, or if the same thing happens when you transfer to a different destination.

The tests you should run:

1) Try the USB device on another PC. Does it have issues with large file transfer?

2) If the USB device is fine, then try a large file transfer over the network or to another internal hard drive on the problem PC running Windows 2008 Server. Does the same issue occur?

3) Double-check to make sure your USB cable is 15 feet long or less.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
[tab][navy]For posting policies, click [/navy]here.

 

[mattlau]

The tests you should run:

1) Try the USB device on another PC. Does it have issues with large file transfer?

2) If the USB device is fine, then try a large file transfer over the network or to another internal hard drive on the problem PC running Windows 2008 Server. Does the same issue occur?

3) Double-check to make sure your USB cable is 15 feet long or less.

1) Yes, the issue exists on other PCs
2) I will verify that soon
3) The cable is 6'

Thanks for the tips thus far. Could this be a limitation for USB 2.0? I know that USB 2.0 isn't exactly stellar when it comes to real-world performance.

 

[mattlau]

Hm, so here is the latest:

Regarding,
2) If the USB device is fine, then try a large file transfer over the network or to another internal hard drive on the problem PC running Windows 2008 Server. Does the same issue occur?

YES!

What could this mean?

 

[victorv]

hi,
I too have noticed that when there are many files
and directories, Windows (Explorer for the precision)
takes time to "prepare to copy"... and "fly" folders.

Try to use programs as Xcopy,robocopy, ecc.: probably
without graphical env, they may go stright to the target.

I always think something relatd to indexed for search.

bye
vic

 

[cdogg]

Because you are having issues copying data to other drives and network destinations as well, I don't believe the USB interface has anything to do with it. Even with the overhead, you should "easily" be getting speeds over 30MB/s.

Are you copying data over the network? If so, try moving data from the internal hard drive to the USB drive. Don't use the network in the transfer. Let's see if that was the problem.

~cdogg
"Insanity: doing the same thing over and over again and expecting different results." - Einstein
[tab][navy]For posting policies, click [/navy]here.

 

[mattlau]

Are you copying data over the network? If so, try moving data from the internal hard drive to the USB drive. Don't use the network in the transfer. Let's see if that was the problem.

I have been copying from the local drive to a USB drive connected to that machine. I am experiencing slow transfer rates on several of my Windows machines under the following conditions:

1) Transferring large sets of small files from a local drive to a USB drive
2) Transferring large sets of small files across the network

When I transfer large files, the rate appears "normal" (CAT-5e speeds for LAN and USB 2.0 speeds for my external drive).

Thoughts?

 

[cdogg]

A large file will usually transfer faster than a group of smaller files of roughly the same size. The hard drive must work harder to gather data that is spread out across the disk. The drive's cache memory isn't as effective either in those situations.

Now when you say a "large" set, are we talking like 50 or is it more like in the hundreds? Does it make a difference if you try to transfer them in groups instead of all at once (say 10-15 at a time)? What happens if you make a ZIP archive of the files and then transfer that one ZIP file?

Also, I know you say you've tried transferring the files to different destinations, but what if the source drive that holds the files is heavily fragmented or is having mechanical issues? I would definitely make sure you've tried transferring the files using a different source drive as well.

 

[jsteph]

I'm just throwing this out there---could the x64 OS be switching to x32 mode for each file?

It's been my experience with our 64 bit servers that they do something similar to what we called in the old days "real mode thrashing", where the os would switch to 'real mode' (for older 286 processors) for each operation when doing some such thing. I notice this when I run Access 2003 on our 64 bit servers--the files and everything are in separate Program Files_X386 directories, and I've notices that I see an hourglass for just a split second on each thing I open in Access--yet this same .mdb on our 32 bit servers and workstations flys with never a spec of hesitation.


It's just a hunch.
--Jim

 

[mattlau]

So I've managed to narrow down the cause of the behavior. Copying multiple files is not necessarily slow, but copying directories within directories is quite slow. Thus, if I have a folder with multiple folders inside it, and multiple files inside those nested folders, copying that root folder will be extremely slow. (Example: copying "Documents" with all of its interior folders and files will be slow, but if I were to just copy all of the documents themselves, without the directory structure, the speed is fast.)

If I simply copy the groups of files, sans the directory nesting, the transfer rate does not suffer.

 

[mattlau]

Update:

The directory nesting is the issue, and it only affects some of our machines (it is not isolated to a single machine). It is particularly noticeable on Windows 2008 x64 and Windows 7 Beta x64.