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

!2I All For example, the 3330 track format for all formatted cylinders except
cylinder 0 is shown in Figure Track 0: RO R1 R2 R3 I I I !I I 8 bytes 4096 bytes 4096 bytes 4096 bytes
Track 1 to Track 18: RO R1 R2 R3
1
8 bytes 4096 bytes 4096 bytes 4096 bytes
igure 7. For.at of 3330 Cylinders for Use by CP All volumes containing space for CP use (paging, spooling, and so on)
must have a properly formatted cylinder O. The only service progra.
that can do this is the For.at/Allocate progra. Cylinder 0 is formatted like other cylinders except that the space
associated with the first three 4096-byte blocks is reserved for system
use. This area is then formatted as illustrated in Figure 8.
Track 0 RO R1 R2 KEY R3
, , \(j r I IPL I DMKCKP I I V I I rec I !odule I 101 VOLID II ILl 8 24 4096 111 4 80 R4 KEY RS KEY R6 FH I , .--- / /----, Allocation I I For.at 1 I For.at I I Byte .ap I I 4 DSCB I I 5 DSCB I I L--//----J 1024 44 96 44 96
Track 1 to Track 18 are the same as the nonzero cylinders.
Figure 8. 3330, 3340, or 3350 Cylinder 0 For.at
Section 4. V8/370 Service Prograas 173