PDSs are limited to 16 extents, 64K tracks, and one volume. https://www.ibm.com/support/knowledgecenter/SSLTBW_2.3.0/com.ibm.zos.v2r3.idad400/allocsp.htm PDSEs are limited to 123 extents and one volume. https://www.ibm.com/support/knowledgecenter/SSLTBW_2.3.0/com.ibm.zos.v2r3.idad400/allocsp.htm
On Sun, Jan 12, 2020 at 2:49 PM Paul Gilmartin <[email protected]> wrote: > > On Sun, 12 Jan 2020 13:59:21 -0500, Matt Hogstrom wrote: > > >Out of curiosity, its been a while since I did storage admin but it occurred > >to me that for the most part a lot of the work in defragging, worrying about > >disk geometry and other issues are really not / less of an issue with cache > >and SSD technologies. So, perhaps naive on my part, but it would seem to me > >the work to “defrag” is really more to keep up the legacy z/OS concepts like > ># of extents, CKD processing for PDS’, etc. Are there benefits to > >defragging these days apart from the consequences of the limitations from > >older architectures and paradigms like directory blocks and member placement? > > > Alas, while the new technologies bypass the performance impact of > fragmentation, insofar as they faithfully emulate older hardware it's > still possible to have virtual space exhaustion. Aren't PDSes still > limited to 65,535 virtual tracks? PDSEs are better at reclaiming space. > > I could imagine a Super-IEBCOPY's updating directory blocks and > DS1LSTAR and reclaiming space so virtually freed. Only imagine. > > Even as SSD firmware moves and remaps physical blocks to > counteract fatigue. > > >-----Original Message----- > On Sun, 12 Jan 2020 09:32:01 -0800, Charles Mills wrote: > > >When you compress a PDS aren't you essentially de-fragging it? No, not the > >way the word is used on PC disks, but you are essentially consolidating > >fragments of free space into one big chunk of free space. > > > >-----Original Message----- > >From: Jeremy Nicoll > >Sent: Sunday, January 12, 2020 1:28 AM > > > >I dunno about the first bit, but "routine mainframe defrag" is fine. > >DFDSS has a DEFRAG verb. > > > I used to believe that DB2 might require a REPRO to reclaim orphaned > CA/CIs. Is that still the case? > > -- gil > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN -- Mike A Schwab, Springfield IL USA Where do Forest Rangers go to get away from it all? ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
