General Procedure for UNLOAD and RELOAD

Take the following steps to unload and reload a database:

Create the new subschema or DMCL reflecting the changes to be made.
Back up all areas to be unloaded and also areas linked to those areas through sets or linked constraints.
Execute the CLEANUP utility if required.
Execute the UNLOAD utility.
Format the areas into which the data will be reloaded.
Execute the RELOAD utility.
Back up the same areas as in step 2.

This procedure may vary slightly depending on the type of change being made.

Output files

The following output files and sort parameters are generated by the UNLOAD utility for use by the RELOAD utility statement:

File	Contents	Size
SYS002	A record occurrence descriptor for each unloaded record occurrence.	For each occurrence descriptor: 24 bytes plus the size of the data portion of the record occurrence.
	A set descriptor for each unloaded record occurrence and for each record occurrence that is not unloaded but has a set connection to an unloaded record occurrence.	For each set descriptor: 24 bytes plus 12 times the number of pointers associated with the record, up to 32 pointers. If the record has more than 32 pointers, it will get an additional set descriptor.
SYS003	An index key occurrence descriptor for each index on a record occurrence.	For each index on each record occurrence: 32 bytes plus the size of the symbolic keys in the index.
SYSPCH	Sort parameters
RELDCTL	A control record with information about the subschema, DMCL, and segment to be used by RELOAD.	60 bytes
	A set descriptor for each set in the subschema.	60 bytes