Page of GC20-1806-9 1s Updated 1pri1 1, 1981 by TNt RespoBses:
The prograas generate messages that indicate successful completion or
errors. Completion messages and codes are returned to the user in the
file indicated by the sfn and sft operands of the GENI8lGE control statement .. Note: Further discussion of the IEBI8AGE utility prograa is contained in the OSLVS nl! PrintiBg Subsystem ProqramJler's·Guide.
Formatting Volumes--General Information Disk Initiaiization
Disk initialization and alternate track assignment should be performed
by the IBCDlSDI utility program on all direct access volumes used in a V8/370 installation, but with the following exceptions: • On 231q and 2319 disks only if there are minidisks, then the
individual ainidisks should be initialized, rather than initializing the real disk. • The 2305 drum should not have alternate tracks assigned. Instead,
defective tracks should be rewired to alternate tracks by the CE.
The rewiring makes the defective track transparent to all
programJling. (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 them.)
Disk FOI'Jlatting 111 direct access volumes used by the V8/370 system (for paging,
spooling, system residence, directory, or temporary disk allocation)
must be properly labeled, formatted, and allocated. The CP
Format/l1locate service program (D8KF8T module) prepares disks for use by 1 eMS Format program is also available and must be used to format C!S and RSCS disks.
All direct access volumes (including both real
to be used by VSA! under C8S, as, or DOS, must
IBCDASDI utility.
disks and minidisks)
be formatted by the
If certain information in the as Format q label on track 0 cylinder 0 is destroyed, no additional alternate tracks can be assigned by IBCDASDI
until the volume is reformatted by IBCDASDI. When either IBCD1SDI or the CP Format/Allocate program (D8KF!T) is used to format a vo1uJle, this
information in the as Format 4 label is preserved. But, when the C8S Format Program formats the volume (or when it formats a minidisk whose
origin is cylinder 0 of the volume) the as Format label is destroyed
and no further alternate tracks can be assigned until IBCDlSDI is used
to reforJlat the volume.
Section 4. V8/370 Service Programs 171

April 1, 1981 Format/Allocate Services Program (DMKFMT)
The Format/Allocate service program formats, allocates, and labels
direct access volumes for paging, spooling and CP file residence. This
service program is executed as part of CP system generation procedures
and may also be executed as a stand-alone program to: • Format direct access volumes for CP use Allocate specific disk areas to particular functions or to CP use • write six-character volume serial number labels
Note: The Format/Allocate program should be used with care since it
destroys existing data (if any). Also, user minidisks and temporary
minidisks must not begin on real cylinder zero of CP-owned volumes,
because information critical to CP is stored in cylinder.
An object deck version of the CP Format/Allocate service program is a
standalone program and can be loaded from a virtual or real card reader
into a virtual or a real machine. (If run in a virtual machine, the
virtual machine must have write access to the volume being formatted.)
The program accepts control statements from the operator's system
console (commands) or from the IPL device (card reader).
Note: Messages DMKFMT736E and DMKFMT13SE may be issued if an available
path to the device cannot be found after an appropriate number of
retries. High activity may cause this situation.
Cylinders used by CP for paging, spooling, and so on, must be
preformatted with fixed length unblocked records of 4096 bytes.
Device capacity when formatted for CP use is:
2314/2319 32 records/cylinder (8 records/S tracks) 3330 51 records/cylinder (3 records/track) 230S 24 records/cylinder (3 reco rds/track) 3340 24 records/cylinder (2 reco rds/track) 3350 120 records/cylinder (4 reco rds/track) The format operation writes 4096-byte blocks on all cylinders being
formatted. The service program does write-checking to verify that parts
of the track are net defective. A count is maintained of pages with
read check errors detected during the format operation. At the
completion of the format operation, the count of the pages with read
check errors is printed.
172 VM/370 Operator's Guide