I am somewhat at a loss to understand how some of the problems you are detailing happened. The only way it could have would be with an ill behaving user written program or process.
Any utility needs to read all 5 stripes in unison (my description, not a technical description), not volume by volume. Striped data for a two stripe data set is written, basically, some on stripe 1, then some on stripe 2, then some more on stripe 1, then back and forth between the two. Any attempt to read all of stripe 1 and then all of stripe 2 will end up with garbage, or at least with data out of order. A user process of skipping the catalog and directly copying volume 1 to tape 1 and volume 2 to tape 2, etc. in an attempt to 'speed up the process' will end up with an unusable bunch of data on 5 tapes. The more common problem I have seen is a user using DISP=MOD to add data to a RECFM=FBS file. On extending a file IOS does not read the last short block and re-write it as a full block, so unless you are very lucky and the last block written was a full block, you will not see the data added to a DISP=MOD FBS data set. Chris Blaicher Principal Software Engineer, Software Development Syncsort Incorporated 50 Tice Boulevard, Woodcliff Lake, NJ 07677 P: 201-930-8260 | M: 512-627-3803 E: [email protected] -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of [email protected] Sent: Sunday, December 08, 2013 1:56 AM To: [email protected] 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
