IBM Professional Series User Manual

format 102 b 800 (recomp)
changes the number of blocks available at virtual address
102 to 800, but does not erase any existing CMS files.
To change only the label on a disk, you can enter:
format 103 c (label)
Respond to the prompting message with a six-character
label.
2. When formatting FB-512 devices, enough blocks of the
minidisk area must be formatted
to support the CMS
disk structure, or message DMS216E will be displayed,
and the
FORMAT request will be terminated. The
number of FB-512 blocks which must
be formatted for
minidisks
of 512, 1K, 2K, and 4K CMS blocksize is 6,
12, 24, and 48, respectively.
3. If the FORMAT command with the RECOMP option
fails and
CMS issues message DMSFOR214W,
"CANNOT RECOMPUTE WITHOUT LOSS OF
DATA. NO CHANGE.," query your A-disk to
determine the number of unallocated blocks. If the
number
of blocks seems adequate, it is possible that
some
of the allocated space is at the end of the disk, and
is thus not available to the
FORMAT command. Issue
the command:
COpy * * A = = = (REP
followed by the FORMAT command with the
RECOMP option.
4. Choosing
an appropriate BLKSIZE to format a disk
depends upon its intended use. A 4K BLKSIZE will
optimize the
I/O if the disk is to contain large files with
no missing records (dense). A BLKSIZE of 1 K
is more
appropriate when creating many small files
or sparse
files.
For example, PL/I regional files are sparse and
they may allocate more space
on a 4K disk than on a 1K
disk, therefore, the smaller BLKSIZE
is preferable.
The larger the blocksize of the disk, the greater the
amount of storage required for
input/output buffers.
7-82 VM/PC Users Guide

IBM Professional Series Specifications

General

Brand	IBM
Model	Professional Series
Category	Software
Language	English