sg_prevent - Man Page



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 (LU)) 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.

Exit Status

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


Written by Douglas Gilbert.

Reporting Bugs

Report bugs to <dgilbert at interlog dot com>.

See Also

sg_start(sg3_utils), sg_persist(sg3_utils)

Referenced By


November 2012 sg3_utils-1.35