RE: Changing the system clock this weekend...

["Graap, Kenneth" <keg@xxxxxxxxxxxxx>]

I was able to get a hold of a "journaling expert" at IBM who informed me that 
my concerns with Application Journaling and system clock time were 
unfounded.... This is good news!

Apparently the commitment control mechanism is NOT sensitive to the timestamps
residing within journal entries.  It is driven, instead, by the CID field 
(commit ID
residing within each journal entry).

Recovery processes using journaled transactions are driven by the CID field too.

The only time timestamp sensitive issue would be issuing an APYJRNCHG command
starting at a specific point AND specifying a timestamp instead of a journal 
sequence number. So, setting the time back could affect recovery procedures in 
the
event of a disaster recovery, if you had to use timestamp parms with APYJRNCHG. 

The issue of Job Accounting / Security journal entries and time sensitive 
processes like replication software and MQSeries are still a real concern 
though. 

Therefore I think I have no choice but to make sure our time change on Sunday 
occurs while the system is quiesced.

I'm not sure how I'll handle the QTIMZON system value issue... If you make any 
changes to this, for example modifying a time zone description using iSeries 
Navigator, the change takes effect immediately!

Therefore, I guess I'll quiesce the system on Sunday, change the QTIMZON system 
value, then power off the system, wait an hour and perform a manual IPL 
verifying that the time is correct as the system comes up.

Thanx to all of you for sharing your thoughts on this ... 

One observation... It really shouldn't be this difficult to make a DST time 
change on the most advanced application server on the planet. I hope a future 
release of OS400 will combine the automated changing to and from DST, with the 
"Time Adjustment" feature so we can SCHEDULE a slow adjustment of the system 
clock over a few hours... After all, there will always be time sensitive 
software and processes running on our systems. I can only hope that IBM hears 
my plea. <smile>  

Kenneth


-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx
[mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Al Barsa
Sent: Thursday, October 26, 2006 11:55 AM
To: Midrange Systems Technical Discussion
Subject: RE: Changing the system clock this weekend...