On 10/12/2009 08:18 AM, Tom Marchant wrote: > On Mon, 12 Oct 2009 06:40:42 -0500, Paul Ip wrote: >> >> I know VVDS can be created Implicltly when a NON-SMS VSAM or a SMS >> VSAM/nonVSAM is created under a 'NEW' volume. >> However, It seems to me that the VVDS (an ESDS itself) is not required to be >> cataloged (meanwhile, some of VVDS are under catalog [MCAT] since we've >> run a IDCAMS DEFINE Explicltly) > > IIRC, the VVDS must be cataloged in any catalog that contains data sets on > that volume which are in the VVDS. If you create a data set that is > cataloged in the master catalog, the VVDS will be cataloged in the master > catalog. If you create a data set that is cataloged in a user catalog, the > VVDS wil be cataloged in the user catalog.
This may have once been true, but I don't think it has been true for years. I don't believe the ability to find and open the dataset depends today on catalog VVDS entries, but instead MVS tracks the VVDS locations of online volumes by some means that no longer require the catalog entry. There are still instances where a VVDS catalog entry will be created and deleted in sync with first and last dataset on the volume in that catalog, but there are other instances where datasets can start using a volume or stop using a volume and the VVDS catalog entries are not managed to keep them in sync. At best the presence of a VVDS entry in a catalog is only a rough approximation of the DASD volume set covered by datasets in the catalog. That remnant of VVDS maintenance that still exists has no doubt been preserved because of its historical use for determining which volumes and catalogs to cross check with DIAGNOSE. Those using this DIAGNOSE technique have learned to expect and tolerate warnings that indicate no catalog-related datasets were found on the volume. This also has implications for the lack of thoroughness of catalog DIAGNOSE strategies that rely only on the catalog VVDS entries to determine what volumes need to be DIAGNOSED against a catalog. Some of the vendors that market their own catalog diagnostic tools look at the VVDS datasets on all the physical volumes and perhaps also check all (non-VVDS) datasets in the catalog to determine an accurate list of which volumes need to be cross-checked with which catalogs. You can't rely on getting that information from the catalog VVDS entries. J C Ewing > >> >> Can anyone give me an advice on which manual tells us that a VVDS (an ESDS >> itself) can be defined without under a catalog (while Using Datasets just >> tell >> not have to be under Master Catalog) > > You might try "managing catalogs" or "using data sets". Or do a search for > VVDS in the DFSMS bookshelf. > -- Joel C. Ewing, Fort Smith, AR [email protected] ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
