DB_UNIQUE_NAME vs DB_NAME in standby databases of ASM file systems

Question

Question : Do we need to have the db_unique_name paramter set differently in standby database compared to db_name in standby .
Problem we are facing :
Here is the little background
Primary Server     : SERVER1
db_name          : VENKAT
db_unique_name     : VENKAT
Standby server     : SERVER2
db_name          : VENKAT
db_unique_name     : VENKAT_stb
Sever          : Linux
Database Version: 11.20.3
File system type: ASM ( 11.2.0.3)
stanby type     : Physical
Disk group names: Identical on both primary and standby servers
Data          : +DATA_OP01027_128
FRA          : +FRA_VENKAT_128
How datafiles are layed out on primary server:
sample datafile name location : +DATA_VENKAT_128/VENKAT/datafile/venkat.277.789579565
How standby was build : using Active duplicte command
Once we have the standby database build we have the datafiles created under this location
Sample datafile name location on standby server : +DATA_VENKAT_128/VENKAT_stb/datafile/venkat.280.789579597
with this we have learnt that the directory VENKAT_stb is getting created in standby ASM off the db_unique_name that
was given in the database , we have not seen this issue in the normal file system even we are using db_unique_name different that
the db_name in standby database .
Can you please help us how we can prevent this situation of having datafiles getting created under differnt direction in standby compared to prod.
Can you also let us know what impacts we might be having if we don't specify the db_unique_name different than db_name in standby database.
Hope this explains the problem what we are facing currently .
What steps i follwed to fix this issues :
I have db_unique_name set to the same name as db_name and when i did the restore all datafiles are in the identical location to prod standby server .
Note : We do fully understand the need for having the db_unique_name set different to db_name in standby db in standby and primary db's are residing on the same physical server .
Thanks
Venkat

Answer 1

first of all, this is not an issue or problem
works as intended
Question : Do we need to have the db_unique_name paramter set differently in standby database compared to db_name in standby .yes
Sample datafile name location on standby server : +DATA_VENKAT_128/VENKAT_stb/datafile/venkat.280.789579597
with this we have learnt that the directory VENKAT_stb is getting created in standby ASM off the db_unique_name that
was given in the database , we have not seen this issue in the normal file system even we are using db_unique_name different that
the db_name in standby database .
Can you please help us how we can prevent this situation of having datafiles getting created under differnt direction in standby compared to prod.well, dont use OMF then
OMF format for datafiles in ASM is: +DISKGROUP/DB_UNIQUE_NAME/DATAFILE/TABLESPACE_NAME.FILE.INCARNATION
datafiles will be created this way no matter what you do
the difference is, that if you dont use OMF, there will be an alias created referencing the file, with the path you gave
for example:
OMF:
create tablespace test size 10M;
a datafile is created: +DATA_VENKAT_128/VENKAT/DATAFILE/test.280.789581212 (i wrote some random numbers here)
non-OMF:
create tablespace test datafile '+DATA_VENKAT_128/dummy/test01.dbf' size 10M;
what actually happens:
a datafile is created: +DATA_VENKAT_128/VENKAT/DATAFILE/test.280.789581212 (i wrote some random numbers here)
and an ASM alias is created: +DATA_VENKAT_128/dummy/test01.dbf
and this alias is used by the database
while OMF files have their specified path format, and their path (db_unique_name) and even name (numbers at the end) will change when duplicated, aliases dont necessarily do this
however this is just extra work and administration, OMF is your friend