On Tue, 27 Jul 2010 12:26:50 +0200, R.S. wrote: >Steve Comstock pisze: >> Barbara Nitz wrote: >[...] >>> PDSEs have only one advantage: They don't need to get compressed. The >>> rest us a huge amount of disadvantages. >>> >>> Regards, Barbara >> And, I believe, multiple members can be written concurrently (I believe; am I right?) How would one do this? Must one OPEN two or more DCBs, one for each member being written? And one might yet wish to be able to append or update in place existing members.
>> Well, they do have at least one other advantage: they can store >> program objects, which allows entry points with long, case-sensitive >> names, which is sometimes handy. > Steve, why would you call that an advantage? I thought you despise case-sensitivity. Anyway, old fashioned PDSes allow case-sensitive (but not long) member names; it's merely higher level interfaces that try to conceal the case-sensitivity. Would you advocate supporting case-insensitivity at the DFSMS layer, similar to Windows? Mac OS X gives the programmer a choice with a granularity of volume. >While I could provide more PDSE advantages than Barbara, I would not >mention long names. > >Reason: I HAVE NEVER SEEN AN APPLICATION WHICH USES THEM. Long names are >not handy for me. Of course I know, there are some... but not in >operating system components. > Isn't this a solution seeking a problem? What interfaces support them? Surely, one can't code // EXEC PGM=Case-sensitive-Long-name? What about ATTACH EP=Case-sensitive-Long-name? What's the format of the word returned by NOTE for a PDSE. It's been discussed here that the low 24 bits contain the relative record number within a member (biased by 0x100000). Do the top 8 bits then identify the member? What happens, then, if a programmer performs BLDL for 257 different members? can the NOTE words identify connections to all? If one performs 2 BLDLs for the same member, are the two returned pointers identical? How do Unix directories compare? o They don't need to be compressed. o Multiple members can be written concurrently. o Members can be appended or updated in place (with a granularity of byte.). o They support long case-sensitive names. o They allow a mixture of program objects and other member types. Deficiencies: o Alias entry points are not supported (AFAIK). o The BPAM support is read-only (so far). Questions: o How do performance and reliablity compare with PDS[E]? I suppose there might be four answers, separate for PDS vs. PDSE and for HFS vs. zFS. o What is the limit on member size? o What is the limit on number of members? -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@bama.ua.edu with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
