2319 minidisks as well as real disks.
l The last cylinder in any 2314 or
2319 minidisk initialized by IBCDASDI is reserved and used as the
"alternate tracks" cylinder. Assigning an alternate track explicitly
will generally be required when a track becomes defective subsequent to
disk initialization or when an intermittently bad track is missed during
disk initialization.
The IBCDASDI program cannot check to see if the 3330, 3340, or 3350 space to be initialized was previously formatted.
If you format only five cylinders of a 5-cylinder virtual disk of a
3330, 3340, or 3350 but specify 20 cylinders to be initialized (CYLNO=20), the IBCDASDI program does not initialize all 20 cylinders
but merely updates the format 5 DSCB in the VTOC to indicate available space, without for the existence of 20 cylinders and without
issuing an error message. Later, any attempt to use the sixth through
the twentieth cylinder causes a Seek Check and the channel program abnormally terminates. When assigning alternate tracks explicitly, IBCDASDI aust find a !glig OS Format 4 label on the disk. If this label has been destroyed (ty CMS Format, for example), or if the label does not apply to the
present disk in its present state (for example, a no longer applicable OS Format 4 label might have been restored to the disk by the DDR
utility), then IBCDASDI must be used to perform the disk formatting function before alternate tracks can be assigned= The reco •• ended
procedure in this case is to: Dump the entire disk to tape using the DDR utility Format the disk using IBCDASDI Assign the additional alternate tracks using IBCDASDI Restore the data to the disk from the tape using the DDR utility IOn the 2305 drum, defective tracks should be rewired to alternate
tracks by the CE rather than being flagged and assigned an alternate in
the usual manner. In this case the fact that a track is defective and
has an alternate wired in is transparent to all programming. (CP itself has no recovery procedures for "software assigned" alternate
tracks on the 2305; however, an operating system running in one of its
virtual machines might make use of +.hem.) Section 4. VM/310 Service Programs 181
The IBCDISDI Frogram: Checks for tracks that were previously designated as defective
(flagged) and have had alternates assigned. The program autoaatically
assigns alternate tracks for 2314/2319 disk devices. This test aust be suppressed when a disk is being initialized with surface analysis
for the first time. This test aust not be suppressed when a disk is
initialized without surface analysis. Performs a surface analysis of each track of a 2314 or 2319 and
automatically assigns alternates (for 2314/2319s), if necessary.
Tracks that are available for use as alternates are checked first. Writes a track descriptor record (record OJ, and erases the remainder of each track. When initializing a disk with surface analysis, IBCDASDI also writes a standard home address. Writes IPL records on track 0 (records 1 and 2). 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 IFL progra., if requested, on track 0 (2314, 2305, 2319, or
track 1 (2311).
The IBCD1SDI Frogram: Checks for tracks that were previously designated as defective
(flagged) and have had alternates assigned. The prograa autoaatically assigns alternates (2314/2319 disk devices only). This
test must not be suppressed. lor 3350 devices, BI/BO on all tracks is rewritten (to facilitate
changing froa · 3330 coapatibility mode to 3350 native aode and vice
versa). Tracks that are flagged defective are surface analyzed and
reclaimed if no errors are detected. The BYPASS and lLIGTEST options
are ignored. The P1SSES=0 option causes "QUICK DASDI" to be
perforaed. Writes a standard hoae address, a track descriptor record (record 0), and erases the remainder of each track. Writes IFt records on track 0 (records 1 and 2). 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 IPL prograa, if requested, on track 0 (2314, 2305, 3330, 3340, or 3350 devices) or track 1 (2311 disks).
182 Vft/310 OFerator's Guide
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