Technical data

Managing Storage Media
9.11 Managing Disk Space
Method Section
Purge files Section 9.11.3
Set version limits on files Section 9.11.4
Set file expiration dates Section 9.11.5
Analyze and repair error conditions Section 9.12
9.11.1 Understanding Disk Quotas
A disk quota is a method for maintaining and enforcing limits on the amount of
disk space available to users on a public volume. You limit the amount of space
available to individual users on public volumes (or volume sets) by creating and
maintaining a quota file on each volume. Individual users can similarly restrict
usage on private volumes.
Quotas are maintained and enforced on a per-volume basis. Each volume or
volume set has its own quota file. A volume on which quotas are not maintained
has no quota file. On a volume set, volume 1 contains the quota file.
With OPER privilege, you (or the user maintaining the volume) supply
identifiers and assign quotas and overdrafts with the System Management
utility (SYSMAN). (During normal file activities, the system automatically
maintains usage counts.)
If users run out of disk space during the creation of a file, they receive a
system message. If they cannot obtain sufficient space by purging or deleting
unnecessary files, they might contact you to increase their disk quota. If they
attempt to write a file to a spooled printer, they must have write access and have
sufficient quota on the disk associated with that printer.
Disk Quota File
A quota file records all users who are allowed to use the disk, and shows their
current disk usage and their maximum disk allocation. A quota file, QUOTA.SYS,
which is stored in directory [000000] with other system files, requires one block of
disk storage for every 16 entries.
A quota file has the following format:
UIC ! Usage " Permanent Quota # Overdraft Limit $
[0,0] 0 333333 3333
[TTD,DAVIS] 15590 333333 3333
[TTD,MORGAN] 1929 333333 3333
[MKT,MORSE] 7650 333333 3333
.
.
.
! User identification code (UIC) of each user entitled to maintain files on the
volume. UIC [0,0] appears in all quota files; use it as a template to set default
values for quotas and overdrafts.
" Number of disk blocks currently dedicated to a user’s files. This number
includes the blocks allocated (shown by the DCL command DIRECTORY
/SIZE=ALL /BY_OWNER=uic), plus at least one block in the index file for
every file owned by the user.
# Maximum number of blocks on the volume that a user’s files can occupy.
When the maximum number is exceeded, the system issues an error message
when a file is created.
Managing Storage Media 9–63