In BS2000, two pubset types can be found: single feature pubsets (SF pubsets) and system managed pubsets (SM pubsets). Both are called via their catalogue ID.
An SF pubset consists of one or more disks whose basic attributes (e.g. disk format, allocation unit, availability) must agree. An SM pubset, on the other hand, can be made up of so-called volume sets with different attributes. The essential attributes only have to agree within each volume set.
When a user defines volume-set-specific attributes for a file on an SM pubset, the system determines a volume set of the SM pubset which matches these attributes and stores the file there. Above all this enables a file to be moved to a volume offering different performance within the same SM pubset without having to change the file name.
For more detailed information on SM pubsets, see the “SMS” manual [18].
An SM pubset under HSMS control is an SM pubset that is managed by HSMS. The HSMS metadata is located on the SM pubset itself. An SM pubset not under HSMS control can only be processed by HSMS in a few cases.
The description below is based on the assumption that the SM pubset concerned is under HSMS control. For simplicity’s sake, it is therefore just called an SM pubset. Wherever there is room for doubt, we expressly indicate whether the SM pubset is under HSMS control or not.
An SM pubset is a closed container that holds data and metadata. The files are located either on the S0 processing level or on the S1 or S2 background levels, depending on whether they contain active or inactive data.
An SM pubset has the following attributes:
Each SM pubset under HSMS control contains just one SM pubset object of the DMS data management system, which is represented by processing levels S0 and S1. An SM pubset consists of several volume sets which together form a pool. The mandatory S0 processing level is made up of one or more volume sets which are not reserved by HSMS; the files for processing must be located on this level.
Storage and background levels are required to save and migrate files of processing level S0 within the SM pubset:
S1 contains files stored and migrated to disk; the S1 level is either formed by a volume set within the SM pubset or by all volume sets under HSMS management.
S2 contains files stored and migrated to tape; the S2 level consists of a tape pool which is implemented by a backup archive directory or a MAREN pool.
To enable the files to be administered on the different levels, the SM pubset environment is described by metadata. The metadata is located in the pool on a specially identified volume set, known as the control volume set. The metadata consists, for instance, of data for the description of the volume set configuration, user catalog, guards catalog, pointers to file catalogs, catalogs for special objects, such as job variables, migrated files, files on private volumes etc. The metadata is stored either in HSMS files on the SM pubset or in HSMS files on the default pubset of SYSHSMS, depending on whether they are system or pubset-specific.
To be able to process an SM pubset as a “closed container”, the term “environment” is used in HSMS. An environment contains data and metadata. An SM pubset under HSMS control is by definition an environment. A different SM pubset is also a different environment.
The data and metadata stored in an SM pubset only relate to objects of that SM pubset. If, during backup/restore or migrate/recall, reference is made to an archive that is defined in an SM pubset, only files and job variables that belong to that SM pubset can be processed. Nevertheless, files backed up in one environment can still be restored to another environment.
The exceptions to this rule are exporting and importing. Exporting and importing are functions that move files from one configuration to another. In other words, these are global functions, i.e. they cannot be allocated to a particular SM pubset environment. These functions are always processed in an SF environment with no restriction on the data to be processed. The metadata (jobs, control file, ...) is physically stored in the SF environment, while the associated data may be stored in any environment.
Archiving and restoring are long-term functions in which the configuration of the environment can temporarily change. They can either be allocated to a computer center configuration, or not. Therefore, these activities can be global or local, i.e. they can be allocated to an SF environment or an SM environment. The metadata (archive, jobs, control file, ...) is physically stored in the related environment, while the associated data may be stored in any environment.
All activities on an SM pubset can even be carried out on another computer or the same computer with another home pubset after the SM pubset has been imported. Interrupted jobs can also be restarted.
The total set of SF pubsets is regarded as a single environment. The data and metadata on SF pubsets can be managed by HSMS.