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This is the last post about HADR, I think I covered most of the basics of HADR finishing off with how it switches primary and standby.  What I have gone over is the basics of HADR.  There are many other topics within HADR.  One important thing to remember is to NEVER do unlogged operations (careful with the load command).  Not only will it ‘break’ HADR standby, but it will not tell you — you’ll not find out until you switch over to the standby to find it unusable.  I believe that in version 9.7, we are being allowed access to the standby.  This will allow you to validate the usability of the standby as well as other things like reporting.

This entry is about how to use HADR.  Once again, just the basics.

The command to switch the primary/standby pair is:

from the standby database:
db2 takeover hadr on database sample

simple as that, the standby is now the primary and the old primary is now the standby.

There is also a feature – ACR (automatic client re-route) which can automatically automatically re-route your client to the new primary database when it can not access the current primary.