EXTENT Record

Contents
vmx32besp
Contents
Use the EXTENT record to assign a contiguous block of disk space to one or more subpools.
[
extentname
] EXTENT 
beginning ending
[
subpool
 ... |
comment
]
Configuration File
EXTENT is defined in the DASD CONFIG file.
Definitions
  • [
    extentname
    ]
    Specifies a one- to eight-character name associated with this extent description. The extentname field is optional and is only used by the IBM System Management API Server; for more information, see the appendix "Systems Management API Support" in the
    Administrators
    . Each extentname statement name must be unique and cannot be used by any other statement in any configuration file.
  • beginning
    Specifies the first cylinder or block number in this extent.
  • ending
    Specifies the last cylinder or block number in this extent.
  • subpool
    ...
    Specifies the names of up to eight subpools, separated by blanks that can allocate space in this extent.
  • *
    comment
    Identifies the fixed CP extent and provides documentation. The
    asterisk
    identifies this extent as a fixed CP extent, and the
    comment
    provides documentation about its use. These comments appear in volume maps produced by the MAP command. No subpool names can be assigned to a fixed CP extent; therefore, no space can be allocated from a fixed CP extent.
    You do not need to identify disk space used by guest SCPs.
Description
The disk space in an extent is allocated through the subpools specified on an EXTENT record. (For more information about subpools, see SUBPOOL Record in the section "Configuration File Reference.")
VM:Secure
assumes that an extent resides on the DASD identified by the VOLUME record that immediately precedes an EXTENT record. This means that, in the DASD CONFIG file, each EXTENT record must appear immediately after its corresponding VOLUME record.
For more information about volumes, see VOLUME Record.
Additionally, SUBPOOL records must appear before they are referenced by an EXTENT record. You cannot continue an EXTENT record beyond one line.
Multiple extents can be defined for a single volume, but they cannot overlap. Minidisk definitions cannot cross over extent boundaries.
Minidisks defined outside extents are not controlled by
VM:Secure
; overlapping minidisk definitions are not detected for these minidisks. All disk space used for CMS minidisks should be identified by EXTENT records.
Minidisk extents can start in cylinder 0 on CKD DASD or in blocks 0 through 15 on FBA DASD. Use caution when using these cylinders or blocks because these areas are used by CP to hold the device’s label and, on CP OWNED volumes, the allocation information. If the CMS FORMAT command is used against a minidisk that starts in these areas, it will re-label the entire device. The ability to define minidisks as cylinder or block 0 is intended for situations in which the device is dedicated to a second-level guest as a full pack minidisk.
Additionally, minidisk extents should not cover alternate areas on a DASD. See the appropriate IBM planning and administration documentation for the location and size of alternate areas for each DASD.
Example
The following EXTENT records, immediately preceded by their VOLUME record, define volume VMPK11:
VOLUME VMPK11 3380 EXTENT  0       001   * CP ALLOC MAP AREA EXTENT  2       401   SYSTEMS DEV1 TEST1 EXTENT  402     552   * CP PAGING AREA #1 EXTENT  553     884   MAIN SYS1 TEMP