I believe an application can create a short FB block in the middle of an output data set with the TRUNC macro. Bill Fairchild
----- Original Message ----- From: "Steve Comstock" <[email protected]> To: [email protected] Sent: Sunday, December 8, 2013 10:00:49 AM Subject: Re: Something to Think About - Optimal PDS Blocking On 12/8/2013 8:58 AM, Jon Perryman wrote: > With the exception of DISP=MOD with multiple open/writes and that the last block will always be, I don't see the difference between FB and FBS. How would FB create a short block in the middle? Well, except for DISP=MOD, it won't: it is a DSIP=MOD situation that allows the possibility. -Steve Comstock > > Jon Perryman > > > ----- Original Message ----- >> From: "[email protected]" <[email protected]> >> To: [email protected] >> Cc: >> Sent: Saturday, December 7, 2013 10:55 PM >> Subject: Re: Something to Think About - Optimal PDS Blocking >> >>> Yes, however FBS stands for Fixed Block Standard, not Spanned. >> Exactly. And the last record in an FBS data set can be "short", i.e. >> less than lrecl. The short record denotes the end of the data set. And all >> the >> utility programs know it and stop processing once they reach the short >> record. >> That is all fine and well as long as we are not dealing with a multivolume >> data >> set. >> >> Think standalone dump written striped to - say - 5 volumes. Each volume has >> a >> data set in format FBS, but only one of the volumes can have a short record. >> SAdump knows that, and IPCS knows it, too. The utilities don't. So assume >> that you took a complete sadump to 5 volumes and the sort record happens to >> be >> on the first volume. Then you use a utility (ICEGENER is my favourite) to >> copy >> somewhere else. You end up with a severely truncated sadump. One fifth, to >> be >> exact. IPCS will read the truncated dump to the best of its abilities, but >> you >> will get all kinds of 'storage not available' warnings when looking at >> the dump. >> >> Last time a customer sent me an sadump, it had 27000cyl. I got all kinds of >> warnings and got lucky in that the sadump messages were clearly truncated >> and >> didn't show the 'successfully finished' message. It turned out that >> the wrong utility was used for copying, and the actual dump had 63000 cyls. >> Visible when IPCS COPYDUMP was used for copying. IPCS knows that a striped >> sadump can have the short record "earlier". >> >> Barbara >> >> ---------------------------------------------------------------------- >> For IBM-MAIN subscribe / signoff / archive access instructions, >> send email to [email protected] with the message: INFO IBM-MAIN >> > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
