It's basically an impossible problem. Only the device, which might have a physical sensor to detect removal, can make a positive determination.
Most devices err on the side of caution -- if they are powering up due to a bus attach, they assume media-change while they were off. Actually, many assume media-change at attachment, because they're not sure if they are attached to the same host. Most media doesn't have a serial number or any way to uniquely identify it. Really, the only safe thing to do is assume media-change on removal/insertion, given that devices (as a generalized term) are inconsistant in their ability/willingness to indicate media change. Matt On Sun, Jul 21, 2002 at 06:27:13PM -0400, Johannes Erdfelt wrote: > Is there a way to revalidate the media is the same as it was before? > > Thinking about it, it may be difficult to do with the variety of media > that's out there. > > JE > > On Sun, Jul 21, 2002, Matthew Dharm <[EMAIL PROTECTED]> wrote: > > That's actually a design feature of the usb-storage driver. We may have to > > change it to accomodate those devices which don't indicate media-change > > properly, unfortunately. > > > > It appears that the 'popular' OSes assume media-change when the device is > > removed/reinserted. Sony MemoryStick devices are notorious for this > > problem. > > > > Matt > > > > On Sun, Jul 21, 2002 at 01:12:49PM -0700, Aurel Wisse wrote: > > > Just for the record Matthew. Yesterday, by accident, I > > > unplugged my Maxtor 3000LE *without* umount, but > > > replugging it without trying to access data on the > > > disk. Interestingly, everything worked fine, as if the > > > scsi layer didn't notice ;-). I was then able to > > > navigate the disk as if it were never gone, and > > > ungplug it cleanly with the umount unplug sequence. > > > > > > I was quite impressed by this. > > > > > > Regards, Aurel > > > > > > > > > --- Matthew Dharm <[EMAIL PROTECTED]> > > > wrote: > > > > Unplug without umount is bad. Autofs is _not_ > > > > designed to handle this > > > > case. > > > > > > > > You need to umount, then eject the device to get the > > > > size change > > > > recognized. > > > > > > > > > __________________________________________________ > > > Do You Yahoo!? > > > Yahoo! Health - Feel better, live better > > > http://health.yahoo.com > > > > -- > > Matthew Dharm Home: [EMAIL PROTECTED] > > Maintainer, Linux USB Mass Storage Driver > > > > Dudes! May the Open Source be with you. > > -- Eric S. Raymond > > User Friendly, 12/3/1998 > > > > > ------------------------------------------------------- > This sf.net email is sponsored by:ThinkGeek > Welcome to geek heaven. > http://thinkgeek.com/sf > _______________________________________________ > [EMAIL PROTECTED] > To unsubscribe, use the last form field at: > https://lists.sourceforge.net/lists/listinfo/linux-usb-devel -- Matthew Dharm Home: [EMAIL PROTECTED] Maintainer, Linux USB Mass Storage Driver Oh BAY-bee. -- Dust Puppy to Greg User Friendly, 12/13/1997
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