Julie...when in NORMAL mode, the recovery log keeps copies of
all 'inflight' transactions....thus the log will grow based on
current backup activity and/or other database update activity.
When a transaction completes, the recovery log space frees up.
When node A finishes its backup, the associated recovery log
space is freed up....ADSM will dynamically reuse this freed space.
Rebooting will also free up the recovery log space.
The more concurrent database update activity you have, the larger
your recovery log will need to be (eg, 20 clients doing backup
at the same time will require a bigger log than 5 clients running
concurrently).  You should monitor your log to ensure there is
sufficient log space to handle your max workloads.


There is one caveat...I believe the recovery log space is allocated
and freed with a wraparound algorithm....this means the space actually
won't be reused until all transactions prior to a given point are
completed and freed up.  This is normally not a problem...but if you
have a particular transaction that is hung up for some strange
reason (normal errors shouldn't be a problem as the transaction is
rolled back and the space freed up that way)....this may slow down
the release of recovery log space for reuse.

Recovery log usage is different for ROLLFORWARD mode....in this
case, ALL database transactions are kept in the recovery log
until a database backup is done...this provides a great deal more
flexibility (and availability) for your database (eg, you can
recover your database to time of failure as opposed to time
of last backup)....but it comes at a price in requiring much
more recovery log space.

...greg tevis


.......
question:
1. Why %Util are reduce from 77.2 reduce to 0.3 after reboot?
2. It seems after the first node backup finished the recorvery log will
   be full and then other node can not backup any more - what problem it
   is?
3. How can I fix it? ( I don't think the add more log space is useful )

Any comments will be appreciated

Thanks in advance
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