2319 minidisks as well as real disks.
l The last cylinder in any2314 or
2319 minidisk initialized byIBCDASDI is reserved and used as the
"alternatetracks" cylinder. Assigning an alternate track explicitly
will generallybe required when a track becomes defective subsequent to
disk initialization or when an intermittently bad track is missed during
disk initialization.
TheIBCDASDI program cannot check to see if the 3330, 3340, or 3350 space to be initialized was previously formatted.
If youformat 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
butmerely 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 aSeek 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present disk in its present state (forexample, a no longer applicable OS Format 4 label might have been restored to the disk by the DDR
utility), thenIBCDASDI 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 theCE 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 allprogramming. (CP itself has no recovery procedures for "software assigned" alternate
tracks on the2305; however, an operating system running in one of its
virtualmachines might make use of +.hem.) Section 4. VM/310 Service Programs 181
l The last cylinder in any
2319 minidisk initialized by
"alternate
will generally
disk initialization or when an intermittently bad track is missed during
disk initialization.
The
If you
3330,
but
issuing an error message. Later, any attempt to use the sixth through
the twentieth cylinder causes a
present disk in its present state (for
utility), then
procedure in this case is to:
tracks by the
the usual manner. In this case the fact that a track is defective and
has an alternate wired in is transparent to all
tracks on the
virtual