Non-IPL Method

The general recommendation is to use the IPL Method as stated above. This protects all time stamp dependent operations on your system as well as BRMS. However, if this is not possible due to operation schedules, you must carefully plan your BRMS activities so that only the system that owns a piece of media will try to update it during the time that system clocks are not yet all reset and the hour is being repeated.

Notes:
  1. Do not perform any BRMS activities during the period of resetting clocks, and during the one hour of repeated time. If you must start backups during the repeated hour, ensure that the system owns enough scratch media for the backups, and that no other update operation will occur on that media during the repeated time period.
  2. If you repeat a period of time by setting the clocks backwards, and during that period, you cause the same volume to be updated, those updates might not be synchronized correctly. BRMS relies upon time stamps on the records to order the records in the file and decide if an update should occur or not.
  3. Save jobs will synchronize an update to the volume information about all network systems to show that the volume is active and owned by the saving system. If one of the other systems had a record for that volume that appeared to be more recent (because that system did not yet have its clock reset), that system would throw away the update record, and synchronize its view of the volume to the other network systems, causing an otherwise valid update to be ignored. It would be possible for BRMS to then overwrite such a tape, and the integrity of your system recovery plan would be compromised.
  4. On the day that times will be changed, you should ensure that while you are doing your nightly saves, no other update activity is occurring for the same volume on another system. The best way to avoid this is to ensure that you have sufficient expired media owned by each system for the backups during this time change period (so that systems will not try to 'borrow' another system's media). Also make sure maintenance, movement, WRKMEDBRM opt 2, and all other update activity do not occur. That way, updates to media records will only be initiated by save activities from systems which already own the volumes.


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