Adabas identifies individual physical blocks within a given database component (Associator, Data Storage, Work) by using a relative Adabas block number (RABN).
The physical blocks within each database component are numbered in consecutive sequence beginning with 1. If the component consists of more than one physical extent (as defined by the operating system), the block numbering is continued across physical extents.
The first track of the first physical extent of the Associator, Data Storage and Work components is not used. The first track of the second and each subsequent physical extent as well as all extents of TEMP, SORT, CLOG, and PLOG is used.
The number of Adabas blocks that can be stored on a given physical unit (track/cylinder/volume) of external storage is different for each database component and for each device type.
Using the information provided in section Supported Device Types, the number of blocks that can be stored on a given volume may be calculated as shown below:
Associator database component, model 3380 (880 cylinders are assumed to be available on the volume).
number of ASSO blocks = blocks/track · tracks/cylinder · number of cylinders = 19 · 15 · 880 = 250,800 Associator blocks
19 blocks must be subtracted for the first track of the first Associator physical extent; therefore, the first Associator volume can contain a maximum of 250,781 blocks.
Data Storage database component, model 3370 (748 cylinders are assumed to be available on the volume).
number of DATA blocks = blocks/track · tracks/cylinder · number of cylinders = 10 · 12 · 748 = 89,760 Data Storage blocks
10 blocks must be subtracted for the first track of the first Data Storage physical extent; therefore, the first Data Storage volume can contain a maximum of 89,750 blocks.
The RABN ranges stored on each VOLSER can easily be determined using the Adabas Online System report function.
