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Re: USB Problems



Somebody in the thread at some point said:
> what is "sync"?

sync is an attribute of the mount that makes every little write get
"sync"-ed to the actual hardware before going on.  Without sync, it does
a "lazy flush" of changed sectors to the actual device a few seconds
(usually) after the first write to it.

Because it often happens the filesystem code or program you are using
write to the same or nearly the same place several times in succession,
it turns out that the lazy behaviour gives a huge speedup, since even if
you wrote a 100 times to a given sector in a few seconds, only one
actual commit of the sector takes place afterwards.  With the "sync"
mount option, you have to dumbly sit through 100 writes to the same place.

You have to take care to umount properly without sync, but it makes
little difference since pulling the stick during writes with sync will
create corruption anyway.

The

# mount

command on its own will show the options in force for each mounted
filesystem.

> and on using lsmod |grep ehci i get
> ehci_hcd               35405  0
> what does this mean?

It means that USB 2 support is present, you should have a look in

# cat /proc/bus/usb/devices

for the stanza representing your USB device.  For example one here looks
like

T:  Bus=05 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#= 86 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=1516 ProdID=8628 Rev= 2.00
S:  Manufacturer=memory
S:  Product=USB2.0
S:  SerialNumber=3059
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=100mA
I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms

The Spd=480 means it is wet up for USB2 "High Speed" that you would want.

-Andy


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