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4 Replies Latest reply: Dec 14, 2012 5:03 AM by user2638923 RSS

db_ultra_safe

user2638923 Newbie
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Hello


Hopefully a simple question but rather long explanation first in attempt to explain exactly what I'm asking!


OS - RHEL6
Version - 11.2.0.3
DG Setup - Primary + Physical standby in High Availability mode with FSFO configured.


We are setting up some database pairs in the above configuration for a new system. According to my reading the parameter DB_ULTRA_SAFE is a 'safe option'. We don't currently know the full usage details of the new system so want to try the safe setting first. If the performance hit is too great then we will look at reducing it.

From what I've read, setting DB_ULTRA_SAFE to DATA_AND_INDEX will effectively do the following:
DB_BLOCK_CHECKING will be set to FULL.
DB_LOST_WRITE_PROTECT will be set to TYPICAL.
DB_BLOCK_CHECKSUM will be set to FULL.

However, I have also read that setting any of the individual parameters will override the DB_ULTRA_SAFE option. Unfortunately I had already set DB_BLOCK_CHECKING and DB_BLOCK_CHECKSUM.

So, now I have returned those two to their defaults (set db_block_checking = false, set db_block_checksum = typical), bounced db then issued:

alter system set db_ultra_safe = data_and_index scope = spfile ;

and bounced the db again. I can see that the DB_ULTRA_SAFE value has taken hold:

SQL> show parameter ultra
NAME TYPE VALUE
db_ultra_safe string DATA_AND_INDEX

however only one of the subordinate parameters looks correct:

NAME TYPE VALUE
db_lost_write_protect string NONE
db_block_checking string FALSE
db_block_checksum string TYPICAL


And finally....onto the question:

What state is the database in? I want it to be in DB_ULTRA_SAFE but it seems only one of the three subordinate parameters actually matches what DB_ULTRA_SAFE should provide.


I could set them all manually but would rather do it 'by the book' and use the governing parameter that's provided.


thanks
Mark

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