[Default] On 19 Jul 2019 04:46:06 -0700, in bit.listserv.ibm-main rel...@us.ibm.com (Peter Relson) wrote:
In looking at the below discussion, I am brought back to the question as to how HPE non-stop (started out as Tandem) manage the update process to avoid a shutdown. Even though it is UNIX based, there are the same logical problems associated with updating running code. Clark Morris ><snip> >If so, perhaps DELAY=255 should be the default. If not, why ever use it? ></snip> >That would never be done. This delays the completion of the command. It is >not up to IBM to decide how long a customer can tolerate that. >What is being deferred, in particular, is the closing of the old DCB and >the free-ing of control structures that goes with that. The update of >address space(s) to use the new LNKLST is done "immediately". > ><snip> >It seems rather obvious that what you would want LNKLIST UPDATE do is >insure that any in-flight or incomplete loads of modules are forced to >complete before the old LNKLST definitions are allowed to disappear, ></snip> >What is also obvious is that that is not possible without crippling the >system, as it would requirel having complete serialization across all >fetches for the complete duration of every fetch. > >Some processes simply cannot tolerate the performance impacts of obtaining >serialization. Compromises are the result. Here, it is the unpredictable >dangerousness. Elsewhere, it might be that storage must be orphaned. Etc. > ><snip> >someone should be able to re-design LNKLST UPDATE so that it is 100% safe >when used within those contraints! ></snip> >Without adding "and never close the old LNKLST DCB", it cannot, while >living within the constraint of having the system remain usable. > >Peter Relson >z/OS Core Technology Design > > >---------------------------------------------------------------------- >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
