FDRCONVT Overview

FDRCONVT converts a DASD volume to or from SMS management without movement of data. It can be used as an alternative to converting data sets to or from SMS management by backing up and restoring them via FDR or FDRDSF or moving them with FDRCOPY.

FDRCONVT can be used to convert a DASD volume to SMS or NONSMS status. The volume is first placed in INITIAL status to prevent new data sets from being allocated while conversion is taking place. All of the data sets on the volume are then converted. If any data set cannot be converted, the volume remains in INITIAL status. Once all of the data sets on the volume have been converted, the volume is placed in SMS or NONSMS status, as specified. Conversion of DASD volumes to or from SMS status can be simulated prior to actual conversion if desired.

FDRCONVT can place a DASD volume in INITIAL status to prevent new data sets from being allocated to the volume in preparation for converting the volume to SMS management. Volumes can be converted to INITIAL status prior to being assigned to an SMS storage group. In order to convert a volume to SMS status, the volume must be assigned to an SMS storage group.

Special processing, such as specifying SMS storage class or management class, can be performed for selected data sets or for all data sets on the volume during conversion to or from SMS status.

Considerations for In-Place conversion

FDRCONVT converts data sets to SMS management in-place without moving any data. Conversion in-place is usually faster than converting the data sets by moving the data, especially if the volume contains only a few data sets. However, there are several disadvantages to this method of conversion:

Conversion in-place does not allow the storage management subsystem to determine where the data sets are to be placed. It is your responsibility to insure that the SMS storage and management classes assigned to the data sets being converted in-place are appropriate. For example, you must insure that a storage class with the AVAILABILITY=CONTINUOUS attribute is not assigned to any data sets on DASD volumes being converted to SMS which are not dual-copy devices.

Because data sets are not moved by FDRCONVT, conversion of a volume in-place may result in the high or low ALLOCATION/MIGRATION THRESHOLD values defined in the storage group for the volume to be exceeded. If the high THRESHOLD value is exceeded, the system may not allocate any more data sets to the volume, or data sets could be migrated off the volume to meet the THRESHOLD values.

The VVDS must be able to expand sufficiently to accommodate class information for all data sets being converted. If there are many non-VSAM data sets on a volume, the VVDS may not be able to get enough space or enough secondary extents to convert all of the data sets. In this case, some data sets must be moved off the volume in order to allow the VVDS to expand.

Important

Performance may be poor on a volume on which the VVDS is in a large number of extents.

If any data sets on a volume cannot be converted to the desired status (SMS-managed or non SMS-managed), the volume remains in INITIAL status. INITIAL status prevents any new data sets from being allocated on the volume. Also, when converting a volume containing multi-volume data sets to NONSMS status, any volumes not specified in the VOL= parameter which contain extents of multi-volume data sets are converted to INITIAL status, since these volumes contain both SMS-managed and non SMS-managed data sets.

Conversion by data movement

The FDRABR, FDRCOPY, and FDRDSF programs can also be used to convert data sets to SMS management by moving data to SMS-managed volumes. Initialize the target DASD volumes with ICKDSF using the INIT command and the STORAGEGROUP and INDEX operands. This creates a VTOC and VTOC index of the desired size and place the volumes in SMS status. The SYS1.VVDS data set is automatically created when the first VSAM or non-VSAM data set is allocated on a volume, or alternatively, a VVDS can be created explicitly before any data sets are allocated. Define a large enough VVDS to accommodate all of the data sets that will reside on a volume.

Once the target volumes are in SMS status, FDRCOPY can be used to move data sets from non-SMS volumes to the SMS-managed volumes. FDRDSF and FDRABR can also be used to restore data sets from backups of managed or non-SMS DASD volumes to SMS-managed volumes.

There are several advantages to converting data sets in this manner. Conversion by data movement allows the storage management subsystem ACS routines to determine the volumes on which the data sets can be placed. This insures that volumes with the proper characteristics are chosen and prevents the converted volumes from having so much data placed on them that the ALLOCATION/MIGRATION THRESHOLDS in the storage group definition are exceeded. The VTOC, VTOC index, and VVDS can be placed adjacent to one another, and a large VVDS can be defined either automatically (the default size for the VVDS is now 10 tracks each of primary and secondary space), or explicitly.

Requirements for conversion

In order to convert a DASD volume to or from SMS status, the volume must be eligible for conversion. DASD volumes that are not assigned to an SMS storage group or which do not have an active indexed VTOC cannot be converted to SMS status. Volumes may be converted to INITIAL status without being assigned to an SMS storage group, but they must have an active indexed VTOC. If a volume is eligible for conversion, it is placed in INITIAL status before conversion of the data sets on the volume is begun.

In addition to the volume being eligible for conversion, all of the data sets that reside on the volume must also be eligible for conversion. If an ineligible data set is found on a volume being converted, that data set is bypassed and conversion continues with the next data set. If all data sets are eligible, the volume is converted to SMS or NONSMS status as specified. If any ineligible data sets were found, the volume remains in INITIAL status. Ineligible data sets must be deleted or moved off the volume before the volume can be successfully converted.

Preparing volumes for conversion to SMS

It may not be practical to attempt to convert all of the data sets on a volume to SMS management at the same time, particularly if new data sets are continually being allocated to the volume. Prior to assigning a volume to an SMS storage group and converting it to SMS status, it may be necessary to quiesce the volume and prevent allocations of new data sets on it. This can be done by using FDRCONVT to place the volume in INITIAL status. New data sets cannot be allocated to a volume in INITIAL status, although existing data sets can be accessed, extended, or deleted. Existing data sets on an INITIAL volume cannot be extended to another volume.

Once the volume is in INITIAL status, no new allocations can take place on it. Data sets that are not eligible for conversion to SMS management can then be deleted or moved to other volumes so that the remaining data sets on the volume can be converted. In this way, the volume can be converted to SMS management over a period of time, so that data sets on the volume remain accessible to users.

As part of the conversion process, FDRCONVT always places volumes in INITIAL status by updating the status indicators in the Format 4 DSCB and the VTOC index prior to converting any data sets on the volume to or from SMS management.

Converting data sets to SMS management

In order to convert a volume to SMS management, all of the data sets on the volume must be eligible for conversion. The following types of data sets are NOT eligible for conversion to SMS management:

ISAM data sets
SYS1.STGINDEX data sets
Uncataloged Generation Data Groups (GDGs)
Uncataloged multi-volume data sets
Unmovable data sets (for example, data sets with DSORG=PSU or POU)
BDAM data sets with OPTCD=A
Active (that is, enqueued) data sets
Data sets for which the ACS routines develop a null STORCLAS
Uncataloged data sets are not eligible for conversion to SMS management if the CATLG=NO parameter is specified, which prevents FDRCONVT from cataloging the data sets in the standard order of search catalog.
Multi-volume data sets are not eligible for conversion unless either all volumes where the data sets reside are specified in the VOL= parameter or the MULTIVOL=YES parameter is specified.

A data set is converted to SMS management by calling the ACS routines to determine the storage class and management class that are assigned to the data set. The ACS routines are called by FDRCONVT in the “CONVERT” environment (that is, &ACSENVIR= “CONVERT”). Data sets for which the ACS storage class routine returns a null SMS storage class are not eligible for conversion to SMS. The data class routines are never called. If the SMS storage class returned from the ACS routines is not null and the data set is otherwise eligible, the data set is converted to SMS management. This is done by creating or updating its entry in the VVDS and BCS to add SMS class information and then updating an indicator in the data set's Format 1 DSCB to indicate that the data set is SMS-managed. Once all of the data sets on the volume have been converted to SMS management, the volume status indicators in the Format 4 DSCB and the VTOC index are updated to place the volume in SMS status. Data set aliases are preserved.

If any data sets on the volume could not be converted, the volume is not converted and remains in INITIAL status. After the ineligible data sets are deleted or moved off the volume, FDRCONVT can be run again to convert the volume to SMS status. When converting to SMS status, data sets that are already SMS-managed are not processed again unless REDETERMINE=YES is specified.

Converting volumes out of SMS management

FDRCONVT can convert volumes in SMS or INITIAL status to NONSMS status. The volume may be may currently be part of a SMS storage group, or not; the reversion works either way. If the volume is currently in SMS-managed status, it must have an indexed VTOC. If the volume is in INITIAL status, it must have an indexed VTOC. In addition, all of the data sets on the volume must be either non SMS-managed already or must be eligible for conversion from SMS management.

Certain types of data sets, including EF (Extended Format) files, can reside only on volumes in SMS-managed (SMS) or INITIAL status. Therefore, volumes containing these data sets cannot be converted to non SMS-managed (NONSMS) status unless they are moved off the volume prior to reversion.

Active data sets, that is, data sets for which a SYSDSN enqueue fails, cannot be converted out of SMS management.

Eligible data sets are converted out of SMS management by removing the entry in the VVDS for non-VSAM data sets, or by removing the SMS class information from the entry in the VVDS and BCS for VSAM data sets. The ACS routines are not called. Once the VVDS entry for the data set has been updated or deleted, an indicator in the data set's Format 1 DSCB is updated to indicate NONSMS status. After all of the data sets on the volume have been converted out of SMS management, the volume state indicators in the Format 4 DSCB and the VTOC index are updated to place the volume in NONSMS status.

Processing specific types of data sets

Uncataloged data sets and data sets not aliased

Multi-volume uncataloged data sets and uncataloged Generation Data Groups (GDGs) cannot be converted to SMS management. Single-volume non-VSAM data sets that are uncataloged or are not cataloged in the catalog to which their high-level qualifier is aliased are converted to SMS management and cataloged unless the CATLG=NO parameter is specified.

If the CATLG=YES parameter is specified or defaulted, uncataloged non-VSAM data sets and non-VSAM data sets cataloged outside the standard order of search are cataloged or recataloged in the appropriate standard order of search catalog (that is, the catalog where the data set's high level qualifiers are aliased).

The INCAT parameter can be used to specify the catalog to be searched for non-VSAM data sets cataloged outside the standard order of search.

Uncataloged VSAM data sets, for example, VSAM data sets that have been deleted with the IDCAMS NOSCRATCH option, cannot be converted to SMS management.

When converting out of SMS management, the only SMS-managed data sets that may be uncataloged data sets are GDGs and temporary data sets. Any other data sets that have a Format 1 DSCB that indicates SMS-managed but are not cataloged are in error and are not reverted.

Multi-Volume data sets

Multi-volume data sets cannot be converted to or from SMS management unless all of the volumes on which the data sets reside are being converted. You may manually include all the volumes containing the multi-volume data sets in the VOL= parameter, or you may specify the MULTIVOL=YES parameter to cause FDRCONVT to automatically process the multi-volume data sets on all of the volumes on which they reside.

For multi-volume non-VSAM data sets, the first volume on which the data set resides MUST always be specified in the VOL= parameter in order for the data set to be converted to SMS management. For multi-volume VSAM data sets, the FIRST volume on which the base cluster's data or index component or any alternate index cluster's data or index component resides must be specified in the VOL= parameter in order to convert the data set to SMS management. This provision – that the first volume where the data set or component resides must be in the volume list when converting to SMS management – applies even if MULTIVOL=YES was specified.

All volumes of a multi-volume data set are processed at once when any extent of the data set is encountered. If any volume on which an extent of the data set resides is not eligible for conversion, then the entire multi-volume data set is ineligible for conversion. All volumes that contain extents of a multi-volume data set must be assigned to the same SMS storage group.

For those portions of multi-volume data sets on volumes that were processed because of MULTIVOL=YES (not included in the VOL= parameter), FDRCONVT flags the Format 1 DSCB of the data set as SMS-managed and sets the status of the volume to INITIAL. To completely convert those volumes to SMS-managed status, you must explicitly run FDRCONVT against them at a later time.

Multi-volume non-VSAM data sets whose catalog entries include candidate volumes are recataloged with the candidate volumes made non-specific when converting to SMS management (that is, the catalog entries for the candidate volumes are changed to “* ”). When converting multi-volume non-VSAM data sets out of SMS management, the candidate volume entries are removed.

When converting to NONSMS status, the first volume on which the data set resides need not be specified in the VOL= parameter, although MULTIVOL=YES must be specified if any extents of multi-volume data sets reside on volumes not specified via VOL=. If MULTIVOL=YES is not specified, then multi-volume data sets that have extents residing on volumes not specified in the VOL= parameter are still converted to NONSMS status. However, the volumes that are not specified in the VOL= parameter are set to INITIAL status, preventing further allocations on those volumes.

VSAM data sets

All parts of an ICF VSAM data set, including Alternate Indexes (AIXs), are converted at once when any component of the data set is encountered. All parts of a VSAM data set, including Alternate Indexes (AIXs) and paths, must be cataloged in the same catalog using an alias in order for the data set to be converted.

Generation data groups

Uncataloged Generation Data Groups (GDGs) cannot be converted to SMS management. Cataloged GDGs can only be converted to SMS management if they are cataloged in an ICF catalog. Model DSCBs cannot be converted to SMS management because they are uncataloged. Since Data Classes replaced Model DSCBs for SMS-managed GDGs (and can be used even with non SMS-managed GDGs), the Model DSCBs can usually be deleted.

When converting to NONSMS status, generations that are not active, (that is, “deferred” or “rolled-off” generations) are uncataloged.

Temporary data sets

Temporary non-VSAM data sets can be converted to SMS management. The Format 1 DSCBs of temporary data sets are marked “SMS-uncataloged”.

The VTOC, VTOC Index, and VVDS

Flags in the Format 4 DSCB and the VTOC index indicate the volume state – SMS-managed, INITIAL status, or NONSMS. The VTOC itself is not a data set and therefore cannot be converted to or from SMS management.

A VTOC index is required on all SMS-managed volumes and volumes in INITIAL status. The VTOC index is converted to or from SMS management along with the other data sets on the volume being converted. When converted to SMS management, the Format 1 DSCB for the VTOC index is marked “SMS-uncataloged”.

A VVDS is required on all SMS-managed volumes that are not empty. The VVDS is converted to or from SMS management along with the other data sets on the volume being converted. To conform to IBM conventions, the VVDS is cataloged into every ICF catalog that is updated for data sets on this volume during the conversion, if it is not already cataloged there.