System Journals

[peteh@xxxxxxxxxxxxxxxx (Pete Hall)]

In message <970807115002_-1741195078@emout16.ma il.aol.com>, From 
SnTCurtin@aol.com, the following was written:
> We are currently journaling after image.  I am trying to find out the
> benifits to journaling before, or both before and after images.  I 
> realize there could be a major impact on disk space if both is 
> implemented, so any thoughts or information you have on this matter 
> would be appreciated.>

Tom,

It depends on what you are trying to accomplish. If its for recovery
purposes, the after image is what you want. That way, you always have
the current state of the database in the journal. If its auditing or
transaction rollback, then you want the before image, because then you
have the earliest possible initial state, who changed it and when. The
current state is the database itself. If you want both, better buy some
more DASD. On the same tack though, does anyone have a rationale for
journalling opens and closes? I don't understand why that might be
useful. Maybe access path lubrication every 1000 hours?

Pete


--
 - Pete Hall peteh@earth.inwave.com
http://www.inwave.com/~peteh/

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* This is the Midrange System Mailing List!  To submit a new message,   *
* send your mail to "MIDRANGE-L@midrange.com".  To unsubscribe from     *
* this list send email to MAJORDOMO@midrange.com and specify            *
* 'unsubscribe MIDRANGE-L' in the body of your message.  Questions      *
* should be directed to the list owner / operator: david@midrange.com   *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *