Re: USB flash drive oddity

[Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>]

:	This (coupled with the fact that Windows never seems to suffer this
:problem) prompts me to wonder if Windows simply never uses the cache
:syncronisation feature and indeed if any umass devices actually require it
:to be used. Disabling it seems to be by far the most common quirk entry.
:Might we get more reliable umass behaviour by making not using it the
:default ?
:
:-- 

    My guess is that windows doesn't for USB devices, and instead probably
    just waits a few seconds and prays that the device flushes out any
    pending writes.  The problem, though, is that there are now many, many
    USB devices which are real hard drives and actually support the command,
    and if you don't flush them before powering down the system (at least
    if the device is powered from the usb port itself), you will lose data.

    In anycase, I think it does make sense to turn off that command by
    default for any USB-attached device, and have the quirk turn it on,
    then just delay a few seconds before doing any power-down action.  If
    someone wants to make those changes I am all for it.

					-Matt
					Matthew Dillon 
					<dillon@backplane.com>