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       sg_prevent - sends a SCSI PREVENT ALLOW MEDIUM REMOVAL command


       sg_prevent  [--allow]  [--help]  [--prevent=PC] [--verbose] [--version]


       Sends a SCSI PREVENT ALLOW  MEDIUM  REMOVAL  command  to  DEVICE.   The
       default  action  of this utility is to prevent the removing or ejecting
       of the medium from a drive. This is done by  ignoring  the  SCSI  START
       STOP  UNIT  command (see sg_start) and ignoring the eject button on the
       drive when the user presses it. Drives that hold removable disks,  tape
       cartridges  or  cd/dvd  media  typically  implement  this command.  The
       definition of the "prevent" codes for this command differ between disks
       and  tapes  (covered  by SBC-3 and SSC-3) and cd/dvd drives (covered by
       MMC-5). The "prevent codes" described here are from MMC-5.


       Arguments to long options are mandatory for short options as well.

       -a, --allow
              allow  medium  removal.  This  is  equivalent  to   setting   to
              ’--prevent=2’.   Cannot  be  used with --prevent=PC option (i.e.
              either use no options (hence prevent removal),  this  option  or

       -h, --help
              output the usage message then exit.

       -p, --prevent=PC
              where  PC  is a prevent code value. Defined values are: 0 allows
              removal, 1  prevents  removal  (default),  2  allows  persistent
              removal  while  3  prevents  persistent removal. "Persistent" in
              this context means that the initiator (port)  that  successfully
              uses  code  3  blocks  other  initiators  (ports)  from allowing
              removal. A "persistent prevent" state  can  be  cleared  by  the
              owner  allowing persistent removal (code 2) or a power cycle (or
              anything that resets the device (lun)) or some special  commands
              (e.g.  various  service  actions  of Persistent Reserve Out, see

       -v, --verbose
              increase the level of verbosity, (i.e. debug output).

       -V, --version
              print the version string and then exit.


       The exit status of sg_prevent is 0 when it is successful. Otherwise see
       the sg3_utils(8) man page.


       Written by Douglas Gilbert.


       Report bugs to <dgilbert at interlog dot com>.


       Copyright © 2004-2007 Douglas Gilbert
       This  software  is  distributed  under  a  FreeBSD license. There is NO
       warranty; not even for MERCHANTABILITY  or  FITNESS  FOR  A  PARTICULAR


       sg_start(sg3_utils), sg_persist(sg3_utils)