Max- Protection - HIGHEST level of data protection and availability for the primary database
1) The redo data needed to recover each trnxn must be written on both the local( online) redo log files and to a standby redo log on atleast one of the standby database.
2) To guarantee no loss of data, primary database will shut down if a fault prvents its from writing to redo data to atleast one stdby db
3) Redo records are SYNCHRONOUSLY transmitted from primy db to stdby db using LGWR process.
3) Trxns committed in the primary has to get confirmation that the trxn is avilable on atleast one standby database.
4) This mode is usually configured with atleast 2 stdby databases
5) Standby redo log files are required for this mode.
6) So, Logical standby db cannot participate in this mode.
7) log_Archive_Dest_n= LGWR SYNC AFFIRM
eg. log_archive_dest_2='service=stdby LGWR SYNC AFFIRM'
Max - Availability - Provides the highest level data protection without affecting the availability of the primary database
1) Similar to max protection. Trxn needs to get acknowledged from atleast one remote standy redo log to commit in Primary database
2) SYNCHRONOUS transmission of the redo data from primary db to standby db using LGWR process
3) the primary db will not shut down if the fault prevents it from writing its redo data to a remote standby redo log.
Instead , primary db will operate in MAX .PERF mode until lthe gaps and faults are resolved.
Once the log gaps are resolved, the primary db will automatically resumes to Max.AVAILABILITY
3) supports both physical and logical.
4) Standby redo logs are required in this mode
5) log_archive_Dest_n should be LGWR SYNC AFFIRM
log_archive_dest_2='service=stdby LGWR SYNC AFFIRM'
Max-Performance- Default Protection mode
1) slightly less prmy db protection than max availability
but with higher perf
2) ASYNCHRONOUS ship of red logs frm primary db to standby using either LGWR or ARCH
3) will not wait for acknowledge from any one of standby database. Transactions will get processed.
4) No affect on performance of primary database
5) Support both physical and logical stdby
6) log_archive_dest_n = LGWR AYSNC AFFIRM or NOAFFIRM
log_archive_dest_2='service=stdby ARCH NOAFFIRM'
or
log_archive_dest_2='service=stdby LGWR SYNC
NOAFFIRM'
1) The redo data needed to recover each trnxn must be written on both the local( online) redo log files and to a standby redo log on atleast one of the standby database.
2) To guarantee no loss of data, primary database will shut down if a fault prvents its from writing to redo data to atleast one stdby db
3) Redo records are SYNCHRONOUSLY transmitted from primy db to stdby db using LGWR process.
3) Trxns committed in the primary has to get confirmation that the trxn is avilable on atleast one standby database.
4) This mode is usually configured with atleast 2 stdby databases
5) Standby redo log files are required for this mode.
6) So, Logical standby db cannot participate in this mode.
7) log_Archive_Dest_n= LGWR SYNC AFFIRM
eg. log_archive_dest_2='service=stdby LGWR SYNC AFFIRM'
Max - Availability - Provides the highest level data protection without affecting the availability of the primary database
1) Similar to max protection. Trxn needs to get acknowledged from atleast one remote standy redo log to commit in Primary database
2) SYNCHRONOUS transmission of the redo data from primary db to standby db using LGWR process
3) the primary db will not shut down if the fault prevents it from writing its redo data to a remote standby redo log.
Instead , primary db will operate in MAX .PERF mode until lthe gaps and faults are resolved.
Once the log gaps are resolved, the primary db will automatically resumes to Max.AVAILABILITY
3) supports both physical and logical.
4) Standby redo logs are required in this mode
5) log_archive_Dest_n should be LGWR SYNC AFFIRM
log_archive_dest_2='service=stdby LGWR SYNC AFFIRM'
Max-Performance- Default Protection mode
1) slightly less prmy db protection than max availability
but with higher perf
2) ASYNCHRONOUS ship of red logs frm primary db to standby using either LGWR or ARCH
3) will not wait for acknowledge from any one of standby database. Transactions will get processed.
4) No affect on performance of primary database
5) Support both physical and logical stdby
6) log_archive_dest_n = LGWR AYSNC AFFIRM or NOAFFIRM
log_archive_dest_2='service=stdby ARCH NOAFFIRM'
or
log_archive_dest_2='service=stdby LGWR SYNC
NOAFFIRM'
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