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Author Topic: USB HDD slowdown when using USB hub  (Read 1804 times)
plutoz
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« on: February 13, 2010, 07:51:27 AM »

I just got my SheevaPlug this week, running Debian Squeeze on an 8GB SD card

I am finding that writing data to a USB attached harddrive (self-powered Vantec enclosure) is VERY slow if I have it connected through my unpowered Linksys USB hub. Here is what comes up in dmesg when the hub is plugged in:

Code:
[47738.565242] usb 1-1: new full speed USB device using orion-ehci and address 8
[47738.717922] usb 1-1: New USB device found, idVendor=0451, idProduct=2046
[47738.724662] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[47738.734238] usb 1-1: configuration #1 chosen from 1 choice
[47738.746874] hub 1-1:1.0: USB hub found
[47738.751547] hub 1-1:1.0: 4 ports detected

Actually the transfers start out 'fast' (6-7MB/sec over GBE LAN link, which seems a bit slow itself) but then drop down to 1MB/sec or less after a few seconds.

Is this problem inherent to all USB hubs with the SheevaPlug?
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plutoz
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« Reply #1 on: February 13, 2010, 08:24:37 PM »

Picked up another brand of USB Hub, this one came with a power adapter - however I tested it and found it worked 1000x better than the Linksys hub without having the power adapter connected. So much for Linksys quality!
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joewein
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« Reply #2 on: February 14, 2010, 05:21:36 AM »

Your Linksys USB hub seems to be  USB 1.1 device:

Quote
[47738.565242] usb 1-1: new full speed USB device using orion-ehci and address 8

Full speed in USB-speak means 11 Mbps = the max. supported by USB 1.1. The USB 2.0 spec also supports what they call "high speed" which offers up to 480 Mbps. "High speed" mode is definitely what you want for attaching mass storage devices.
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plutoz
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« Reply #3 on: February 15, 2010, 05:08:38 AM »

grrr, you are absolutely right. who in this day and age sells a usb 1.1 hub....

I assumed 'full speed' was high speed  Undecided

All is good now, loving my sheevaplug!
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