You can optionally convert the entire database in one BPGSIZE run or split the database conversion process over a multiple BPGSIZE runs.
The following three phases must always be differentiated, regardless of how many BPGSIZE runs are used to convert the database:
Conversion of the database directory (dbname.DBDIR)
Conversion of the database compiler realm (dbname.DBCOM) and all user realms (dbname.realm-name)
Update run: among other things, BPGSIZE reads in auxiliary files that have not been processed and updates the remaining DBTTs; if conversion to a larger page format is involved, the COBOL subschema directory
(dbname.COSSD) is also converted here.
The realm being currently processed can be determined from the runtime messages of BPGSIZE.
When realms which do not participate in distributable lists are converted, only the realm which is to be converted plus dbname.DBDIR and dbname.DBDIR.NEW are required. You can therefore temporarily swap out all other original and converted realms in the database (to create space for converting the realm which is currently being processed).
You cannot convert a realm which is being used by a distributable list on its own. Instead, you must convert all realms which belong to a distributable list S in the same BPGSIZE run. The set of realms which can be converted in a BPGSIZE run must be closed with respect to distributable lists.
A set of realms is closed with respect to distributable lists when it is assigned the characteristic that for every realm of the set which is used by any distributable list S every other realm which is used by the same list S is also contained in the set.
If, for example, SX is a distributable list with the realms R1, R2, R3 and SY is a distributable list with the realms R2, R4, R5, the realm set R1, R2, R3, R4, R5 is closed with respect to distributable lists. The set R1, R2, R3, on the other hand, is not closed with respect to distributable lists as R2 is contained in the set, but realms R4 and R5 which belong to the same list SY are not.
Required realms
The following overview shows which realms are required by BPGSIZE to convert the database directory (dbname.DBDIR), the database compiler realm (dbname.DBCOM), and the individual user realms. The required realms must be made available on magnetic disk during the period required for conversion.
The following are required to convert the database directory:
the original database directory dbname.DBDIR
the file dbname.DBDIR.NEW for the converted database directory. This file is created by BPGSIZE by default.
The following are required to convert the database compiler realm:
the original database compiler realm dbname.DBCOM
the file dbname.DBCOM.NEW for the converted database compiler realm. This file is created by BPGSIZE by default.
the original database directory dbname.DBDIR
the converted database directory dbname.DBDIR.NEW
The following are required to convert a user realm dbname.realm-name:
the original user realm dbname.realm-name
the file dbname.realm-name.NEW for the converted user realm. This file is created by BPGSIZE by default.
the original database directory dbname.DBDIR
the converted database directory dbname.DBDIR.NEW
Apart from the original database directory (dbname.DBDIR), the original realm is no longer required by BPGSIZE for conversion as soon as that realm has been fully converted. The original database directory, by contrast, is no longer required only after the entire database has been converted.
System environment of BPGSIZE
The following diagrams show the system environment of BPGSIZE in the individual conversion phases.
System environment when converting the DBDIR
Figure 36: System environment of BPGSIZE when converting the DBDIR
System environment when converting the DBCOM and user realms
The following system environment is required by BPGSIZE in order to convert the database compiler realm (dbname.DBCOM) or a user realm (dbname.realm-name):
Figure 37: System environment of BPGSIZE when converting the DBCOM or a user realm
In the case of the database compiler realm, the realm-name in figure 37 realm-name refers to the DBCOM.
System environment during the update run
Figure 38: System environment of BPGSIZE during the update run
The COBOL subschema directory (COSSD) is converted only if the database is being converted to a larger page format.
Converting the database in one BPGSIZE run
If the entire database is converted in a single BPGSIZE run, the three phases of conversion are combined automatically by BPGSIZE in that run. This is typically achieved by calling BPGSIZE with REALM-NAME=*ALL in the CONVERT-DATABASE statement (see "Statements for BPGSIZE").
When a database is converted in one BPGSIZE run, the individual realms are converted sequentially. This could result in unacceptably long conversion times for large databases.It is therefore advisable to only convert small databases in one BPGSIZE run.
Converting the database in multiple BPGSIZE runs
If you want the database conversion to be distributed over multiple BPGSIZE runs, you will need to ensure the correct sequence for the conversion yourself.
To convert the database in multiple BPGSIZE runs, proceed as follows:
Create the converted database directory (dbname.DBDIR.NEW) in the first BPGSIZE run.
This first BPGSIZE run could also be used to convert the database compiler realm (dbname.DBCOM) and/or user realms of the database.You can now convert the remaining realms of the database in further BPGSIZE runs. Note that it is also possible to call BPGSIZE concurrently for individual realms. This may be meaningful in some cases, since the time required to convert a realm essentially depends on the size of that realm.
Exception:
As only realm sets which are closed with respect to distributable lists can be converted in one BPGSIZE run (see "Conversion phases"), realms of a distributable list cannot be converted in parallel.
The following factors should be taken into account when deciding whether to convert realms sequentially or in parallel:
Sequential realm conversion requires less memory, but generally results in longer runtimes.
Parallel realm conversion requires more memory in the short term, but speeds up the conversion of the database.
Now start the update run by calling the BPGSIZE with REALM- NAME=*ALL in the CONVERT-DATABASE statement (see "Statements for BPGSIZE"). If a conversion to a larger page format is involved, BPGSIZE will automatically convert the COBOL subschema directory (dbname.COSSD.NEW) as well.
All realms for a distributable list must be converted in the same BPGSIZE run.
Restarting an aborted BPGSIZE run
If a BPGSIZE run is aborted due to a small FPA area in the converted realm, for example, you will need to restart the aborted BPGSIZE run. This should be done by starting BPGSIZE again with the same statements so that BPGSIZE is prevented from processing fully converted realms again.