Daylight saving time

The time change causes problems for WebSphere MQ for iSeries because WebSphere MQ uses timestamps based on the system clock to access data in the queue manager's journal. If the system clock changes while WebSphere MQ is running, WebSphere MQ can fail to access journal data correctly. Therefore, quiesce WebSphere MQ before changing the system clock.

For i5/OS V5R3 and later, there is an automatic method available to adjust the clock using the Time Zone system value (QTIMZON). If you use the Time Zone system value, it complicates the time change problems for WebSphere MQ for iSeries because it automatically adjusts the time without a chance to quiesce WebSphere MQ before changing the system clock. You are not recommended to use the Time Zone system value when WebSphere MQ for iSeries is actively being used on an i5/OS system.