Control Data 3170 Installation Handbook page 196

BAD TRACK FILE ALLOCATION
11
Effective use of mass storage requires that faulty tracks be removed from availability.
This is done by identifying the bad tracks and downing them. A track is downed by
declaring it nonavailable in the SYSTEM - BA DTRACK file.
Identification of faulty tracks is provided by the manufacturer, the customer engineer,
system error recovery, and from tests run by the operator under the bad track
utility routines described in the MSOS Operator's Guide.
The SYSTEM-BADTRACK file must be allocated if bad track utilities are to be used.
This file is used to store a map of all known defective tracks in the system.
The file should normally be allocated as shown by the following cards. If the block
size is altered, modifications must be made to the bad track utility routines.
$FET, MSOS, SYSTEM-BADTRACK, 8192, 00, 0000, 0000
$ALLOCA TE, n, 991234, , seg, dt
The value of n for various device types is as follows:
853/854/841 2
813/814 1
CAUTION
If the number of defective tracks known to any
single MSOS system exceeds 1022, the system
bad track file size must be increased.
11.1 BAD TRACK FILE INITIALIZATION
The system bad track file must be initialized with the UPALL staten1ent. This state-
ment clears the area allocated for the file so that all tracks will initially be set as up.
The following sample job illustrates the use of the UPALL statement.
$JOB" ,
$BDTRCK, lu
UPALL
END
77
EOF
88
$EOJ
60410800 D
lu is the logical unit from which bad track statements are read
11-11-1