Input Processing Output Notes 1 If the track bypass is not selected,
a track check is performed on the
user-specified track. If the track is good, a message is issued. IBC1091 TRACK CHK INDICATES
TRACK IS GOOD 2 The ASGNALT routine flags the given
track as defective and assigns an
alternate. If the defective track is a
primary track, the primary track is
flagged and an alternate track is
assigned. If the defective track is an
alternate track that was not assigned
to a primary track, the alternate
track is flagged as defective. However,
if the defective track is an alternate
track that was assigned to a primary track, the alternate track is flagged and
another alternate is assigned to the
primary. Then, the TRKPRNT routine causes
a message to be printed stating the
address of the defective track and its
assigned alternate. IBCllOI BAD TRACK cccchhhh IBCllll ALTERNATE cccchhhh
3 Field six of the VTOC is decremented
to indicate that one less alternate
track is available, field five is
incremented to point to the next available alternate track.
Module IBCDASDI IBCDASDI IBCDASDI If specified, track check is
performed.
2 Flag defective track, assign
alternate.
3 Update the VTOC. Label Ref Notes ) GETALTX Control is then given to location
GETAL T to repeat the process for
GETALT2 the next user-specified track, or, if
none exists, to initiate normal
end of job. Control returns to CPo ASGNALT
TRKPRNT
GETALT4
Diagram 1-3. Assigning Alternate Tracks
8 IBM VM/370 Service Routines Program Logic 8 VTOC Module Label Ref

Program Organization IBCD1SDI -- GENERAL INFORMATION VM/370 initializes virtual disks with the OS utility program IBCDASDI. IBCDASDI formats real or virtual VM/370 disk volumes for OS, DOS, and VSAM use. It should not be used to format CP disk areas (for
paging, spooling, and so forth), or non-VSAM CMS disk areas. The execution of IBCDASDI is performed from the virtual card
reader. IBCDASDI can, in addition to initializing
real disks, initialize a minidisk. A
ainidisk can be initialized with or without
a surface analysis (a test for defective
tracks); a surface analysis should be
included when a ainidisk is initialized for
the first time. Tracks in the last
cylinders of a 2314 minidisk are left open
for assignment as alternate tracks. No
tracks are saved for alternates on 3330,
3340, or 3350 ainidisks. PROGRAM DESCRIPTION This section describes the program logic of
the IBCDASDI program. The IBCDASDI program does the following: • For non-3330 devices:
Checks for tracks that were
previously designated as defective
(flagged) and have had alternates
assigned.
Automatically assigns alternate
tracks for 2314/2319 disk devices
but not 33305, 3340, and 3350. This test must be suppressed when
a disk is being initialized with surface
analysis for the first tiae. This test
.ust not be suppressed when a disk is
initialized without surface analysis. • For 2314 and 2319 devices: Perforas a surface analysis of each
track
Automatically assigns alternates, if
necessary. TraCKS that are available for use as
alternates are checked first. • For all devices: Writes a track descriptor record
(record 0), and erases the remainder
of each track. IECtASDI also writes
a standard home address. Writes IPt records on track 0 I ___ ...,._A'_ 1 __ ;I ",), \.L. O;::\"V.L. Ui:) I au .... Writes volume label on track 0 (record 3) and provides space for
additional records, if requested.
Constructs and writes a volume table
of contents (VTOC). Writes IPt program, if requested, on track 0 (for all DASD devices exceFt
2302, 2303, and 2311) or track 1
(for 2302, 2303, and 2311). • For all devices except 3330 and 3340,
checks for tracks that were previously
designated as defective (flagged) and
have had alternates assigned. The
program automatically assigns alternates
(2314/2319 disk devices only). This
test must not be suppressed. • For 3340 and 3350 devices, rewrites the home address and track descriptor record
on all tracks. Tracks flagged defective
are surface analyzed and reclaimed if no
errors are detected. The BYPASS and FtAGTEST options are ignored. The PASSES=O option will cause "QUICK DASDI" to be performed. • For all devices: Writes a standard home address, a
track descriptor record (record 0), and erases the remainder of each
track. Writes IPt records on track 0 (records 1 and 2). Writes voluae label on track 0 (record 3) and provides space for
additional records, if requested.
Constructs and writes a voluae table
of contents (VTOC). Writes IPt program, if requested, on
track 0 (for all tASD devices except 2302, 2303, and 2311) or 1
(for 2302, 2303, and 2311).
Chapter 1. IBCDASDI--The Virtual Disk Initializaticn Program 9