Chapter 3. Storage management subsystem environment
3.2 SMS constructs for fast replication
DFSMShsm manages the fast replication backups, and recovery can be performed at the copy pool level, the volume level, and at the data set level.
In this section, we describe the DFSMS constructs that are used to manage DFSMShsm fast replication.
3.2.1 Copy pool
A
copy pool
is the SMS construct that defines the storage groups that must be processed collectively by the DFSMShsm function. A copy pool can contain the names of up to 256 storage groups that must be processed collectively for DFSMShsm fast replication.Naming conventions
The name of this type of construct can be up to 23 characters. The first character of the name can be an uppercase alphabetic or national character. Any of the remaining characters can be an uppercase alphabetic character, national character, or a number.
What does
What does
it look like?
it look like?
What are its
What are its
requirements? requirements? Where is Where is it placed? it placed? Data Data Class Class ACS Routines Storage Storage Class Class Management Management Class Class Storage Storage Group Group
Defining a copy pool
When you define a copy pool, the individual source pool storage group names are entered. The actual volumes that are associated with each storage group are retrieved during subsequent processing. The volumes that are processed during a function, such as fast replication backup, might not be the same volumes that are associated with the storage group at the time that the copy pool was established. For example, if volumes are added to a storage group within a copy pool, those volumes will be processed as part of the next fast replication backup automatically. The copy pool definition does not need to be updated unless storage groups are added or removed from the pool.
An individual storage group can be associated with up to 50 different copy pools.
Backup versions
As many as 85 backup versions can be maintained for each copy pool. Each version that is maintained requires a unique target volume for each source volume. If you are specifying five backup versions, five target volumes must be available for each source volume that is associated with the copy pool. All target volumes must be available when the FRBACKUP command is issued for execution.
Dump copy
You can request for a dump copy to tape for each volume that is backed up during the FRBACKUP of a copy pool by automatic dump processing of DFSMShsm.
Recovery processing
DFSMShsm can record catalog information of all data sets that are being allocated on the volumes of the copy pool. This record is a prerequisite for the support of moved or deleted data sets when you request to restore individual data sets during FRRECOV processing. If you want to use a fast replication backup for recovering the entire copy pool, even before the background copy completes (the Fast Reverse Restore function), special processing is necessary during FRBACKUP. You must plan to use Fast Reverse Restore and specify it during the copy pool definition in the ISMF Copy Pool Define panel (Figure 3-5 on page 35). To preserve the full duplex status of a Metro Mirror volume pair when the target volume in a FlashCopy relationship is at the same time a primary volume of a Metro Mirror volume pair, you can request to preserve the full duplex status as part of the copy group definition (Figure 3-4 on page 34).
3.2.2 Copy pool backup storage group
The special storage group type of copy pool backupwas introduced when DFSMShsm fast replication was first introduced with z/OS DFSMS V1.5. It is intended to contain only the candidate target volumes for a certain copy pool storage group.
Volumes in a copy pool backup storage group
Volumes that are associated with a CPBSG are reserved for DFSMShsm use. SMS Source Control Data Set (SCDS) validation will fail if a CPBSG is assigned for allocation by the SMS ACS storage group selection routines. When you try to delete or open a data set on one of these volumes without using DFSMShsm fast replication (for example, by using ISPF DSLIST services), an error will occur. The error message says that the data set is not cataloged. Therefore, you cannot change the contents of a copy pool backup volume outside of the control of DFSMShsm.
Storage group status
The SMS status of storage group and volume is used during data set allocation and
end-of-volume extend. The SMS status of a CPBSG and volume is not used by DFSMShsm during a fast replication request. (For example, a status of DISABLE NEW or DISABLE ALL does not prevent DFSMShsm from processing the volume.) You can restrict DFSMShsm access to a volume in a CPBSG by varying the volume offline to z/OS.
Every pool type storage group that is part of a copy pool must be associated with a CPBSG. Usually, this association is established by populating the associated field in the pool storage group definition that refers to a particular CPBSG. Only pool storage groups can define associated CPBSGs. A pool storage group can specify its own CPBSG or specify a CPBSG that is shared by multiple pool storage groups.
Source and target volumes
For each source volume in a storage group to be copied, enough eligible target volumes in the CPBSG must exist to satisfy the needs of the number of specified backup versions. Otherwise, FRBACKUP processing will fail.
An eligible target volume must conform to the following requirements:
Have the same track format as the source volume.
Be the exact size of the source volume.