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

The 1BCDASD1 program can assign
alternate tracks for real 3330/3340/3350 volumes only when they are specified by
the GETALT statement. Even with the
GETALT statement, the 1BCDASD1 program cannot assign alternate tracks for a 3330/3340/3350 minidisk because no
cylinder has been allocated on which to
assign alternate tracks. Defective
tracks are flagged and alternate tracks
are assigned when the 3330/3340/3350 storage volumes are initialized at the
factory. An 1BCDASD1 job that
initializes a 3330/3340/3350 performs
the "Quick DASD1" function, which reads
alternate tracks, decrementing the total
unit of alternates by one whenever an
alternate is found defective or
assigned, writes a volume label and VTOC, and writes an 1PLTEXT if requested. No surface analysis is
performed and no home address or record
o is written on the primary tracks. The BYPASS and FLAGTEST options of the DIDEF statement are ignored. DASD 3340 disk packs are factory-shipped
without flagged tracks and alternate track
assignments. 1BCDASD1's "Quick DASD1" detects 3340 customer-generated alternate track assignments.
The IBCDASD1 program cannot check to see
if the 3330, 3340, or 3350 space to be
initialized was previously formatted.
The absolute loader gives control to the START routine. After the control
statements are read and analyzed,
control is passed to: VOLCHK GENSE
if volume label checking and
virtual disk initialization are
requested.
if virtual disk initialization
without volume label checking
is requested. GETALTYZ if alternate track assignment
is requested. OPRTAB A list of valid command words
used on control cards. 10 IBM VM/370 Service Routines Program Logic KEYTAB A list of valid key words used
on control cards. SY1NTAB A list of valid input devices
for control cards. DEVTAB A list of valid devices handled
by the IBCD1SDI program. PROCBUFF 1 list of constants for specific device types. COBVTIB I tatle used to convert console
input to upper case. IOTAE I tatle used to convert hexadecimal to EBCDIC graphic.
ALTTT I tatle used to convert EECtIC graphic to hexadecimal. TIB13 TABS! A buffer of hexadecimal zeros (X'OO') for disk and drum
surface analysis. A buffer of hexadecimal E5s (X'ES') for data cell surface
analysis. Also used as a
buffer of hexadecimal 55s (X' 55') for disk and drum surface analysis. None
External References ---The-program-enters an enabled wait state
shortly after it is loaded. An attention interrupt identifies the
virtual machine console and the INPUT control statement is read. This control statement tells IBCDASDI which device to
read to get the program control
statellents.
Exit Conditions ---Successful-completion of DMKMDA results
in a wait PSi with E's in the address
field. An end of job lIessage is also
given on the message device.
Error exits result in E's being loaded
in the address field of a wait PSi. Error stops, whenever possible, are preceded by a message which defines the
error. Machine check interrupts result
in the loading of a PSi in the wait
state with E2 in the address field.