sg_prevent - sends a SCSI PREVENT ALLOW MEDIUM REMOVAL command


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


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 --prevent=PC).
-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 SPC-3).
-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 PURPOSE.


sg_start(sg3_utils), sg_persist(sg3_utils)

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