> fopen / append > write one record with timestamp and the 24 bytes of collected data > fclose
Are you saying that I will not then end up with 24-byte "physical" blocks, or did you not consider that part of my original post? Yes, I agree, if the writer has the file allocated for only a brief period then some sort of collision logic is manageable. I would prefer to write it in Rexx but C++ is not out of the question. I hope I have long since written my last "large" assembler application. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Bernd Oppolzer Sent: Saturday, June 18, 2022 10:37 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: Some UNIX file usage questions I would use one single normal MVS dataset and make the started task every 15 minutes do the following: fopen / append write one record with timestamp and the 24 bytes of collected data fclose this will last only microseconds, and your file can have any desired blocksize. (I assume that you are writing the program in C and that you can use the C runtime system, but if it is ASSEMBLER, it should work as well). The reporting programs can access the file at any time, with the exception of the small period of time when the started task is doing the update. If this makes you feel unsecure, you can make your reporting programs check how long ago the started task made its last update or so (say: if there is enough time to complete the report) ... or another sophisticated method of making sure that there will be no trouble. I didn't think much about this, but I'm sure there are several clever methods to synchronize the (one) writer and the many readers. For me, it does not make a real difference if the file is a MVS dataset or a Unix file ... but I must admit, I have not much experience with Unix files on MVS. It would indeed make a BIG difference, if I had a DB2 database; then I would not think a second about concurrency. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
