$READBLK MDR Analysis for bad VTS Block Sizes 08/05/04 THERE ARE NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. The Package: IBMTOOLS.EXE Self-Extracting Zip file. This will expand into three separate files: IBMJCL.BIN, IBMCNTL.BIN, IBMLOAD.BIN IBMJCL.BIN - Execution JCL for BADBLKSZ jobstream. IBMLOAD.BIN - Program code for executing BADBLKSZ. By analyzing the MDR (Miscellaneous Data Records) from SYS1.LOGREC or the EREP history file, we can identify tape volumes that are writing small blocks to the VTS and causing extended job runtimes. There is an often over-looked paramater in COBOL that should be specified on the File Definition Statemant to insure adequate blocking. Apply-Write-Only (AWO) allows a COBOL program using RECFM=VB to fill the block before writing. Without the parameter, COBOL will check to see if there is room in the current block for the maximum LRECL. If not, it will write the block with the existing data and start a new block. If a program was writing 300 byte records, but specified DCB parameters of RECFM=VB, LRECL=32756, BLKSIZE=32760 the program would end up writing blocks of 304 bytes (300 data + 4 RDW). The following jobstream has been created to help analyze these records. See installation procedure in member $$INDEX. 0. EREPMDR - JCL to extract MDR records from EREP history file. 1. BADBLKSZ - Program that reads either SYS1.LOGREC or the EREP history file, finds volumes writing small block sizes, then gets jobname and dsname from a TMS copy. Installation at the customer site: Use the procedure described in IBMTOOLS.TXT.