Hi Andy!
Yes, level 0 still requires scanning of every block and it will take
longer to do L0 than it would take to do L1. However, that is offset by
the fact that you have only a single backup to restore. And you must
restore a full backup. The performance hit doesn't really matter since
the backup is taking place on the standby, as per OP. The best of both
worlds is what Pap has said: to have a backup suite capable of merging
L1 and L0 backup into a new L0 backup. That is known as "synthetic full
backup". He essentially keeps doing incremental backup forever and
merging them into a new full backup on the daily basis. I would really
like to know which backup software he's using.
Commvault can do that, but it requires storage snapshot. I am not sure
that Commvault can snapshot ZLDRA, Oracle would have to reveal their
internal mechanisms on the appliance for that, so it's probably not
Commvault.
Regards
On 5/14/21 9:26 AM, Andy Klock wrote:
Admittedly, it's taken me a bit to follow your line of thought. As
an example, if a level 0 is taken on Sunday and the six
incremental backups are taken on consecutive days, you are
asserting that it would be better to instead take level 0s every
day.
I can see how deduplication can speed up writes and possilby
conserve space for the backups, but there is still is a
performance hit with this strategy, right?
Level 0s still require scanning every block which takes time, so
with BCT, RMAN already knows what has changed and the incrementals
are going to complete much faster than dedplucated level 0s.
Do you have some test cases that prove this strategy?
Thanks,
Andy K
