On Sun, 21 May 2017 14:19:39 -0500, Paul Gilmartin <paulgboul...@aim.com> wrote:
>On Sun, 21 May 2017 05:12:00 -0500, Elardus Engelbrecht wrote: >> >>>RACF (I'm less sure) is VSAM. >> >>No, it is PSU (PS and Unmovable). Other attributes are mandated by IBM. >> >"Unmovable" would seem to imply uncopyable; the copy would have to go >in a different place. But there must be some provision for backing it up, >and little point in trying to move it to another system with such as FTP. "Unmovable" is recommended to ensure that other tools don't move an active copy of the RACF database to a different location on the DASD volume, since they cannot tell that it's OPEN and in use. There is nothing actually location-sensitive within the database, except that it must be one contiguous allocation. > >Why not VSAM? Performance? Antiquity? It feels as if RACF has a >built-in DB engine. The RACF database format and processing pre-dates VSAM, or was possibly being developed concurrently. (I've forgotten the exact details.) I did look, many years ago, at what would be required to switch RACF to using VSAM, and it would have required significant redesign, redevelopment, and testing. Also, given the way that RACF initializes, and the fact that the database is accessed directly and concurrently from all address spaces on the system as well as from multiple systems, it was not clear that using VSAM would even be feasible. Yes, RACF has a kind of non-relational DB engine built in. We also considered at one point whether it might be possible to switch to using DB2, but we didn't want to limit RACF's usage to those customers willing to license DB2, too. (And, of course, if we did switch there's the redesign, redevelop, test expense to consider, too.) There were also migration and compatibility considerations, of course. If you have several systems sharing one RACF database it would not be appropriate to require all of them to have to upgrade to new RACF (or z/OS) releases simultaneously so they could all switch to VSAM- or DB2-based databases. And allowing a mixture of old-style databases and new-style databases would be extremely complex. We did that once when we changed the RACF DB from using a 1K blocksize to using a 4K blocksize, and it was complex. But switching to an entirely different mechanism like VSAM or DB2 would be even more of an undertaking. -- Walt ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
