Read the following it mite help: http://www.linuxjournal.com/article.php?sid=6867
And --------- quate ------------- Why USB Devices Mount Read-Only In the December 2003 issue, an article by Rick Moen on the use of USB Flash storage devices (�Floppies for the New Millennium�) includes the following: �...no matter what you do, the Flash disk always mounts read-only....Exactly why /bin/mount insists that the Flash disk is write-protected and must be mounted read-only is a genuine mystery.� I am the author and maintainer of the driver that talks to this entire class of devices. To me, it's not a mystery. USB mass storage devices are handled by a virtual HBA in the SCSI subsystem. For direct-access type devices (disks, Flash, etc.), sd.c checks the write-protect status with a MODE_SENSE command. The problem is, MODE_SENSE isn't used by Microsoft Windows. Thus, the firmware to recognize, process and respond to that command properly often is lacking from USB devices, especially those that are under extreme price pressure, such as the keychain-type Flash devices discussed in the article. Sometimes, they simply respond with incorrect data. This problem is widespread. I've even seen quite a few devices that crash their internal firmware when they see certain MODE_SENSE or MODE_SENSE_10 commands. This is basically a matter of poorly implemented devices�the device is tested with a popular OS and not fully coverage-tested for compliance to the open and published specifications. Up to a certain 2.4.x kernel version, a failure of the check for write-protect would default to write-protected status. Often this is accompanied by a message from the kernel (sd.c: test WP failed, assuming write protected). Later, a patch was merged that made the assumption write-enabled. The 2.5/6 kernels introduced a new problem�sd.c wants to check for mode page 8, which causes more devices to die. Currently, those of us involved with USB storage development are trying to identify what MODE_SENSE/MODE_SENSE_10 commands are used by Microsoft Windows to speak to these devices�the theory is that if we can identify these commands, then they must be safe for Linux to use. -- Matthew Dharm Author/Maintainer, Linux USB Mass Storage Driver ----------------------------- Erez > ----- Original Message ----- > From: "Boris Zingerman" <[EMAIL PROTECTED]> > To: <[EMAIL PROTECTED]> > Cc: <[EMAIL PROTECTED]> > Sent: Monday, March 01, 2004 4:32 PM > Subject: Disk On Key support in Linux > > > > Hi > > > > Which Disk On Key devices are well supported in > Linux ? > > ( Do they all use the same protocol ?..) > > > > Thanks. > > > ================================================================= > To unsubscribe, send mail to > [EMAIL PROTECTED] with > the word "unsubscribe" in the message body, e.g., > run the command > echo unsubscribe | mail > [EMAIL PROTECTED] > __________________________________ Do you Yahoo!? Yahoo! Search - Find what you�re looking for faster http://search.yahoo.com ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
