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Old 08-03-2014, 06:13 AM   #1
AntBla
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Will plugging and unplugging USB many times cause problems


Hi.
I use my linux box to back up my SD cards.
I leave the box on all the time.
Each time I plug a card it adds a new USB device number.
Is there an upper limit to this number or can I reset it?
Will it cause problems if the number goes too high.
Here is what it looks like in dmesg
Code:
[ 9987.399540] usb 1-1.5: USB disconnect, device number 18
[ 9991.727688] usb 1-1.5: new high-speed USB device number 19 using dwc_otg
Thanks all.
V.
 
Old 08-03-2014, 09:49 AM   #2
gengisdave
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the upper limit should be 127; this is the max number of devices you can connect to a USB controller
 
Old 08-03-2014, 10:31 AM   #3
jefro
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Not sure I've ever heard of any issue where the number is exceeded.

What happens to the sequence would be something you may be able to tell us in a few years when it either reaches the limit or starts over or stops.

Things change often so it may or may not be possible to map or fool the system so that a device is used each time as some assigned number. Doubt you need to do it in this case.
 
Old 08-03-2014, 01:02 PM   #4
lleb
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Quote:
Originally Posted by AntBla View Post
Hi.
I use my linux box to back up my SD cards.
I leave the box on all the time.
Each time I plug a card it adds a new USB device number.
Is there an upper limit to this number or can I reset it?
Will it cause problems if the number goes too high.
Here is what it looks like in dmesg
Code:
[ 9987.399540] usb 1-1.5: USB disconnect, device number 18
[ 9991.727688] usb 1-1.5: new high-speed USB device number 19 using dwc_otg
Thanks all.
V.
the real thing to worry about it the labeling of the USB device by the system. are you using any kind of automagic mounter (ie: Gnome III or KDE) or are you mounting manually via the /dev/sd# or better yet are you using UUID.

with UUID in either autofs or fstab you will bypass the notices above as the system will realize that its the same device and not care to count up.
 
  


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