HP 3000 Manuals HP 3000 Manuals
KSAM XL File Size Reduction Enhancements by Alwin Okuna Commercial Systems Divisions Overview You can now reduce the size of your KSAM XL files by specifying that an optimal data block size be selected. To get optimal blocking, the data block size selected is based on the record size. Previous versions of KSAM XL used a 4K byte data block size. This remains the default data block size if you do not specify the selection of an optimal data block size. If you typically have large record sizes, this enhancement will greatly benefit you. In addition, to significantly reducing the size of you KSAM XL files, you may see performance gains due to the compaction of the data records. With this new enhancement, the version for the KSAM XL files has been changed to "2" to reflect the change to KSAM XL files. KSAMPARAM Changes Now you can specify that KSAM XL select a data block size that will be an efficient space utilization of the data area upon the creation of a new KSAM XL file. During HPFOPEN/FOPEN, bit 8 in the flags word of the KSAMPARAM array may be set by you to indicate that KSAM XL should select a data block size. If you do not set this bit, the block size defaults to 4K. Changes to the FILE, BUILD, LISTEQ, and LISTFILE Commands Two new parameters, OPTMBLK and DEFBLK, have been added to the FILE and BUILD commands. OPTMBLK allows KSAM XL to choose an optimal data block size. The DEFBLK parameter defaults to a data block size of 4K. If neither parameter is specified, DEFBLK is used as the default. The LISTEQ command now displays the values of these two new parameters. LISTFILE,7 has been enhanced to display the version and the bit 8 setting in the KSAMPARAM array. FFILEINFO and FLABELINFO Changes The FFILEINFO intrinsic has a new item number, 92, which returns the version of the file. Two new items have also been added to the FLABELINFO intrinsic. Item 50 will return the KSAMPARAM information in the file label extension. Item 51 will return the version in the file label extension. Copying KSAM XL Files By using a file equation and FCOPY, a KSAM XL file can now be copied to a new KSAM XL file either with a 4K data block size or with an optimal data block size. If you have existing KSAM XL files of 4K you can also convert your files by using FCOPY, specifying that KSAM XL select the optimal data block size in the file equation. If the file equation does not specify either option, FCOPY will use the bit 8 setting in the FROM file's KSAMPARAM array. Moving New KSAM XL Files to Previous Releases If a KSAM XL file was created using the new optimal blocking, you may need to convert the file back to the default blocking of 4K before using it with releases prior to MPE/iX Release 5.0. First, enter LISTFILE,7 to determine whether optimal blocking had been selected. If optimal blocking was selected, use FFILEINFO item #68 to determine the file's block size. Files with block sizes that are not 4K should be converted. This can be done by issuing a file equation specifying the default blocking and using FCOPY to copy the old file to a new one.
NOTE When a KSAM XL file with an optimal data block size other than 4K is dscopyed to a pre-5.0 system, DSCOPY creates the new file with a data block size of 4K and issues a warning to you that the data block sizes are different. The new file is written with the information from the original file.