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?
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
