TP # 12

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FECO:

TP # 12

MODIFICATION NO:

N/A

PRODUCT:

TAPE DECKS ON NCR SVR4 SYSTEMS

SUB-ASSEMBLY:

N/A

ESTIMATED MAN HOURS:

N/A

CLASS OF CHANGE:

INFORMATIONAL

REASON FOR CHANGE:

PROBLEMS OF DIFFERENT BLOCK SIZES ON TAPES.

RELATED FECO/AB

N/A

TAPE BLOCK LENGTH ON NCR SVR4 SYSTEM TAPES

NOTE: Throughout this FECO a SPACE in a string is shown by a Ñ .

              All other spaces are purely cosmetic

        Introduction

        On NCR 3000 systems running SVR4, it has been experienced that restoring a tape generated with a different block-size can
        take a long time. It can be shorter if the block sizes are the same.

        NOTE That all commands in this document must be run from root #

        To determine current block length.
        To interrogate a tape drive to determine the current block length enter

                tcm Ñ –d Ñ device Ñ -i

                i.e, tcm Ñ –d Ñ / dev / rmt / c0t3d0s0 Ñ -i

        To set fixed block length.
        To set a fixed block length then enter,

                tcm Ñ –d Ñ device Ñ – b blocklength

                i.e. tcm Ñ –d Ñ / dev / rmt / c0t3d0s0 –b512

        To set variable block length
        To set a variable block length enter the following

                tcm Ñ –d Ñ device Ñ –b0

                i,e, tcm Ñ –d Ñ / dev / rmt / c0t3d0s0 Ñ –b0

        NOTE * A tape must be present in the drive to change the block size. A tape drive will default to a variable block length
        upon reboot.

        To set a permanent fixed block length.
        If a fixed block length is required permanently, then a script will have to be created in the /etc/rc2.d directory.

        To do this enter,

                # vi Ñ / etc / rc2.d / S99tcm

                I to insert

                tcm Ñ –d Ñ device Ñ – b blocklength

        Then ESC : wq!

        NOTE* Again this would only set the block length upon reboot if there is a tape present in the drive.

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