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Conference turris::digital_unix

Title:DIGITAL UNIX(FORMERLY KNOWN AS DEC OSF/1)
Notice:Welcome to the Digital UNIX Conference
Moderator:SMURF::DENHAM
Created:Thu Mar 16 1995
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:10068
Total number of notes:35879

8805.0. "SCSI LOCATE command supported?, implemented?" by MQOOA::LEDOUX (Vincent [email protected]) Wed Feb 12 1997 09:37

    Is the SCSI LOCATE command supported for magtape under
    Unix?  I cannot find any reference about it.
    
    If not how hard would it be to implement?
    Writing a whole new driver?
    
    Any input welcome.
    
    Vince.
T.RTitleUserPersonal
Name		DateLines
8805.1Answered offlineMQOOA::LEDOUXVincent [email protected]Wed Feb 12 1997 14:1121
    For the posterity:
Subj:	Re: Notefile TURRIS::DIGITAL_UNIX Note 8805.0 

Vince,

    Is the SCSI LOCATE command supported for magtape under
    Unix?  I cannot find any reference about it.
The SCSI LOCATE command is defined as an optional command by the SCSI-2
standard and is not implemented in the Digital Unix tape driver.

    If not how hard would it be to implement?
    Writing a whole new driver?
From a software point of view, it wouldn't be too difficult to implement.
But we would need to requalify all our supported tape drives.

As an alternative, I suggest the use of REWIND and SPACE commands to get
to your desired location.  These are implemented as subcommands of the
MTIOCTOP ioctl (see the mtio man page).  FYI, in the ptmin release
of Digital Unix (V4.0d), the tape driver keeps track of the tape position.
This position, along with a bunch of other status, is available using
the MTIOCGET ioctl.