Splitting the KDCFILE

In order to improve the I/O behavior of your application, you can split the KDCFILE by swapping out the page pool and/or the restart area of the KDCFILE. Splitting the page pool and restart area across several files is particularly advantageous if you have very high transaction rates, since openUTM then distributes the number of access operations to these areas across the various different files.

The administrative data is essentially stored in the main file KDCA. The swapped-out page pool or restart area can be split between several files by means of generation. Provided this results in the use of numerous different hardware paths, access times can be reduced considerably thereby enhancing performance.

Generation notes

You can use the following operands of the KDCDEF control statement MAX to define the areas of the KDCFILE to be swapped out during generation, and to specify the number of files created for these areas:

• Page pool files

  MAX...,PGPOOLFS=number

• Restart area files

  MAX...,,RECBUFFS=number

In the case of dual-file operation, which is defined using the statement
MAX...,KDCFILE=(....,DOUBLE), these files are also maintained twice.

File names

The individual files of the KDCFILE that are contained in the swapped out areas have the same base name filebase as the main file KDCA and have the following names:

• Page pool files: P01A, P02A, P03A, ... .
  If you are keeping a dual KDCFILE, the files P01B, P02B, P03B, ... are also created.

• Restart area: R01A, R02A, R03A, ... .
  If you are keeping a dual KDCFILE, the files R01B, R02B, R03B, ... are also created.

Example

You want to set up your KDCFILE as follows:

• Page pool distributed across two files.

• Restart area located in a separate file.

• Duplicated file names.

For the base names, the place holder FILEBASE is used in this example.

On Unix, Linux and Windows systems, FILEBASE is the directory in which the files are stored, and can be replaced, for example, by /home/userutm/base (Unix and Linux systems) or C:\userutm\base (Windows systems).

In the KDCDEF generation you specify the following MAX statement:

MAX...,KDCFILE=(FILEBASE,DOUBLE),PGPOOLFS=2,RECBUFFS=1,...

KDCDEF then generates the following files:

	KDCFILE	Original	Copy
BS2000 systems:	Main file containing administrative data	FILEBASE.KDCA	FILEBASE.KDCB
	Page pool	FILEBASE.P01A FILEBASE.P02A	FILEBASE.P01B FILEBASE.P02B
	Restart area	FILEBASE.R01A	FILEBASE.R01B
Unix and Linux systems:	Main file containing administrative data	FILEBASE/KDCA	FILEBASE/KDCB
	Page pool	FILEBASE/P01A FILEBASE/P02A	FILEBASE/P01B FILEBASE/P02B
	Restart area	FILEBASE/R01A	FILEBASE/R01B
Windows systems:	Main file containing administrative data	FILEBASE\KDCA	FILEBASE\KDCB
	Page pool	FILEBASE\P01A FILEBASE\P02A	FILEBASE\P01B FILEBASE\P02B
	Restart area	FILEBASE\R01A	FILEBASE\R01B