Re: Logon during night backup on tape

[daparnin@xxxxxxxxxxxxxx]

> The major problem with "Save-While-Active" is ensuring that the
> transactions are synchronized during the backup. For example, suppose
> you have a program that saves a particular transaction in three
> different files (and records). It could happen that your backup saves
> FILE1 sans RECORD1 and, after that, your app runs and writes the three
> records. A short time later, your backup saves FILE2 and FILE3. At
> that moment, your backup data is inconsistent.


Save-while-active is the way to go.  Synching isn't a problem if you 
approach the shutdown properly.  If you temporarily end QINTER and quiesce 
subsystems that might have jobs with record locks it's pretty 
straightforward.  We went from having the system down for about 2.5 hours 
to about 20 minutes.  (That was on our old 720.)  Ending jobs and shutting 
things down is the hardest part.  Once that's done you can have a job that 
sits in its own job queue monitoring a message queue waiting for the 
message that the checkpoint has been established.  After that, you can 
resume normal operations.  If you try to start a SWA in an uncontrolled 
manner then you probably will have issues.  It's too bad that Al Barsa 
isn't around to campaign for save-while-active.  He really helped me with 
it.

Having said that, we now have zero downtime.  We just end mirroring to our 
DR-system and do the backup on it.


Dave Parnin