John, You are absolutely correct. The aim of SDB is to maximise the space used on a track, and not to simply do half track blocking.
An LRECL of 7000 with RECFM=VB will get a blksize of 27998 from SDB, but for FB a BLKSIZE of 7000 will realise more data per track. If SDB did half track blocking there would be 13996 bytes wasted per track. There are probably other ranges of LRECL that SDB will not generate half tracks blocks for besides LRECL=7000 to 7548. For example a LRECL of 18432 will not get half track. Ron > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[EMAIL PROTECTED] On > Behalf Of John P Kalinich > Sent: Wednesday, 15 February 2006 12:03 AM > To: IBM-MAIN@BAMA.UA.EDU > Subject: Re: DASD allocation guidelines > > I have found that DSORG PS and PO don't always get half track blocking > with > SDB. For example, SDB picks a BLKSIZE of 7000 for LRECL 7000. > > Regards, > John Kalinich > Computer Sciences Corp > > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
