How are Time Zones handled in UIM?
Related: What information does tz_offset column in CA UIM database RN tables indicate?
UIM 9.x or later
UIM records a "tz_offset" value in the RN_QOS_DATA tables for each sample received.
The tz_offset is based on database server time and indicates how far away from GMT the current DATABASE time is.So tz_offset should be the same for all samples.
Suppose you have 2 servers, one in EST time zone and one in MST time zone which is 2 hours behind.
Database server is located in PST which would be 3 hours behind the EST server.
Sample is gathered at 11:00:00 EST.
Sampletime on the database gets recorded as 08:00:00PST with a tz_offset of 28800 because the database is 8 hours behind GMT.
At the same exact time, a sample is gathered from the machine in Mountain Time, where it is 9:00:00EST.
Sampletime on the database should STILL be recorded as 08:00:00PST with a tz_offset of 28800. Because 8:00:00PST, 9:00:00MST, and 11:00:00EST are all the same time, so it doesn't matter what time zone the server is really in.
The times are calculated based on the following:
- the "sampletime" value given in a QOS_MESSAGE coming from a probe
- the tz_offset value in the same message
- the tz_offset value on the RN_ tables (database server timezone)
When a sample comes in, data_engine calculates the difference in tz_offset between the sending server and the database server and records the samplevalue in "local database server time".
Then when the customer views the data in OC/UMP or SLM, they would see the "local" time zone when the data was collected, based on the time zone of the viewer themselves. So if you are in EST and you look at the results from 11:00:00EST the timestamps (in UMP) should say 11:00:00EST. If you go to MST and look at the exact same data, the results in UMP should show 09:00:00MST since it's based on what time zone the viewer is in and these times are the same time in "real time".
Note :This is also why database/UMP/OC/PH servers should all be in same timezone, so these calculations will be accurate.