To clarify: the below-the-line storage issue resulted from having multiple tape output files with DCB=BUFNO=10, a holdover from the days of slow I/O. Writing these with 262KB buffer sizes led to a radical increase in the use of below-the-line storage; the simple solution was to eliminate the BUFNO parameter or set the value to 2. In the event of reoccurrence, we will be revisiting REGION and using values of 32M or higher, to maximize availability of below-the-line storage and to make sure that above-the-line storage is not contributing to the problem.
Discussion is invited, as we have arrived at these policies internally through negotiation between DBAs, Operations staff, and z/OS Systems programmers. --Phil -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Sevetson, Phil Sent: Thursday, August 16, 2012 12:19 PM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: ADRDSSU Large block performance My site saw big improvements in DB2 z/OS (Image Copy) backup elapsed times. We're implementing LBI, but have encountered problems with below-the-line storage for batch IMS writing sequential files, and with IMS GSAM, which does not read files larger than (BLKSZLIM) 32760. Fixes were needed from Syncsort and from Compuware for FA/MVS. --Phil Sevetson, DB2 DBA *************** -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of Mark Jacobs Sent: Thursday, August 16, 2012 11:59 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Re: ADRDSSU Large block performance Really? Our results (full volume dumps) haven't shown any major improvements. Mark Jacobs On 08/16/12 11:54, Scott Barry wrote: > Yes, significant elapsed time improvement, to start. > > Unfortunately, there are instances where someone has hardcoded BLKSIZE= which > overrides the LBI benefits. Consider scaning the tape management catalog, > looking for these improvement opportunities (removing any/all DCB parameter > values). > > Scott Barry > SBBWorks, Inc. > > On Thu, 16 Aug 2012 08:51:27 -0400, Martin, Mike<mike.mar...@ncsecu.org> > wrote: > > >> All, >> >> >> >> We are upgrading to z/OS 1.13 from 1.11. ADRDSSU will now use BSAM and >> blocks of 262k (1.11 used 65k). >> >> >> >> Has anyone seen big benefits in their shop from this change? >> >> >> >> Mike Martin >> >> </PRE>This email may contain confidential and privileged material for the >> sole use of the intended recipient. If you are not the intended recipient, >> please contact the sender and delete all copies. Any review or distribution >> by others is strictly prohibited. Personal emails are restricted by policy >> of the State Employees' Credit Union (SECU). Therefore SECU specifically >> disclaims any responsibility or liability for any personal information or >> opinions of the author expressed in this email. >> >> </P> >> >> --------------------------------------------------------------------- >> - For IBM-MAIN subscribe / signoff / archive access instructions, >> send email to lists...@listserv.ua.edu with the message: INFO >> IBM-MAIN >> > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN > > -- Mark Jacobs Time Customer Service Tampa, FL ---- The Doctor: You know when grown-ups tell you everything's going to be fine, and you think they're probably lying to make you feel better? Young Amy: Yes. The Doctor: Everything's going to be fine. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
