Re: DST and CICS journaling
SFS will anyhow scan its logs to check what it has to do at restart (rollback/foward recovery from last checkpoint/xxx), and this not only after the clock change,but maybe also a bit later if it were to abend. Maybe you can execute the procedure "Replacing Both File Pool Log Minidisks", chapter 7 in the SFS admin book. I guess in this order: - shut SFS down cleanly - change the HW clock - reIPL but do NOT start SFS - replace the logs 2009/10/18 Shimon Lebowitz > Kris wrote: > > > As far as I understand, CICS uses the local time in its logs, not UTC > (and > > that's the reason that CICS must be kept down). So keeping CICS down for > > an hour will be enough. What the HW clock is doesn't matter for CICS. > > So I would need CICS to be down 1 hour *IF* I was > changing "local time". Since the procedure I described > was to start at local-8PM and remain at local-8PM > (by changing the HW *and* the offset), I should be > able to restart CICS immediately. > > > But, if you'd have DB2, that will use UTC -or more exact: the HW clock- > in > > its logs (just like SFS), playing with the HW clock may mean you have to > > keep them down ... > > Oh!! SFS uses HW time?! So will I need to leave all my SFS > servers down for 3 hours? (In my planned procedure, local time > remains 8PM, but HW clock changes from 9PM [with offset -0100] > to 6PM [with offset +0200] ). > > If I did an orderly shutdown of VM, would I still need > to worry about SFS? If each server was shut down, > aren't all outstanding transactions ended? Why would the > logging be a problem? > > > Thank you for any clarification! > Shimon > > > > > My question is: If I now > > > -- shut down my system at > > > 8PM local time, when our hardware clock is 9PM > > > (according to our current settings: the hardware is still set > > > to local summer time), > > > -- and I change the hardware clock to > > > 6PM (UTC, 2 hours behind standard local, and 3 behind > > > summer local), > > > -- and set the VM timezone to 'standard local' at UTC+2, > > > which will be 8PM > > > > what will happen with CICS? > > > Do I need to have it down for 3 hours (since the HW clock went > > > from 9PM to 6PM) ?? > > > Or can I start it up immediately (since the VM local time > > > stayed 8PM) ? > > > > > -- > > Shimon Lebowitzmailto:shim...@iname.com > VM System Programmer . > Israel Police National HQ. > Jerusalem, Israel phone: +972 2 542-9877 fax: 542-9308 > > -- Kris Buelens, IBM Belgium, VM customer support
Re: DST and CICS journaling
Kris wrote: > As far as I understand, CICS uses the local time in its logs, not UTC (and > that's the reason that CICS must be kept down). So keeping CICS down for > an hour will be enough. What the HW clock is doesn't matter for CICS. So I would need CICS to be down 1 hour *IF* I was changing "local time". Since the procedure I described was to start at local-8PM and remain at local-8PM (by changing the HW *and* the offset), I should be able to restart CICS immediately. > But, if you'd have DB2, that will use UTC -or more exact: the HW clock- in > its logs (just like SFS), playing with the HW clock may mean you have to > keep them down ... Oh!! SFS uses HW time?! So will I need to leave all my SFS servers down for 3 hours? (In my planned procedure, local time remains 8PM, but HW clock changes from 9PM [with offset -0100] to 6PM [with offset +0200] ). If I did an orderly shutdown of VM, would I still need to worry about SFS? If each server was shut down, aren't all outstanding transactions ended? Why would the logging be a problem? Thank you for any clarification! Shimon > > My question is: If I now > > -- shut down my system at > > 8PM local time, when our hardware clock is 9PM > > (according to our current settings: the hardware is still set > > to local summer time), > > -- and I change the hardware clock to > > 6PM (UTC, 2 hours behind standard local, and 3 behind > > summer local), > > -- and set the VM timezone to 'standard local' at UTC+2, > > which will be 8PM > > > what will happen with CICS? > > Do I need to have it down for 3 hours (since the HW clock went > > from 9PM to 6PM) ?? > > Or can I start it up immediately (since the VM local time > > stayed 8PM) ? > > -- Shimon Lebowitzmailto:shim...@iname.com VM System Programmer . Israel Police National HQ. Jerusalem, Israel phone: +972 2 542-9877 fax: 542-9308
Re: DST and CICS journaling
As far as I understand, CICS uses the local time in its logs, not UTC (and that's the reason that CICS must be kept down). So keeping CICS down for an hour will be enough. What the HW clock is doesn't matter for CICS. But, if you'd have DB2, that will use UTC -or more exact: the HW clock- in its logs (just like SFS), playing with the HW clock may mean you have to keep them down ... 2009/10/15 Shimon Lebowitz > Here in Israel we have already changed our clocks back, > but I need to understand a bit more about how CICS journaling > works with time changes. > > Until now, we have always had our hardware on local time. > (As you may guess, the Israel Police Dept. is not exactly > a multinational globe-spanning enterprise). > Because of an open PMR which had us very worried about doing > an IPL for our clock change, what we actually did was: > > 1) define a VM timezone with an offset of -1 hour > 2) close down CICS and VSE, and log off the VSE machine > 3) SET TIMEZONE in VM > 4) wait 1 hour > 5) restart VSE, whose time is defined as having an offset of zero >(NOT zone=VM!) > > This was my idea, because of the worry over the open PMR, but > actually I have wanted to work with SET TIMEZONE for years, > and the powers that be resisted it for whatever reasons. > > Now that everyone saw how much easier it was, I want to > schedule a real IPL (the PMR has been solved!) and set the > hardware clock to UTC so I can use two timezones: > standard time at UTC+2 and summertime at UTC+3. > > My question is: If I now > -- shut down my system at > 8PM local time, when our hardware clock is 9PM > (according to our current settings: the hardware is still set > to local summer time), > -- and I change the hardware clock to > 6PM (UTC, 2 hours behind standard local, and 3 behind > summer local), > -- and set the VM timezone to 'standard local' at UTC+2, > which will be 8PM > > what will happen with CICS? > Do I need to have it down for 3 hours (since the HW clock went > from 9PM to 6PM) ?? > Or can I start it up immediately (since the VM local time > stayed 8PM) ? > > Thanks for any explanations, > Shimon > > > -- > > Shimon Lebowitzmailto:shim...@iname.com > VM System Programmer . > Israel Police National HQ. > Jerusalem, Israel phone: +972 2 542-9877 fax: 542-9308 > > -- Kris Buelens, IBM Belgium, VM customer support
