When
new disks are added to the ASM cluster, the database files are automatically redistributed across
30 Oracle Database 11g DBA Handbook
all disk volumes for optimal performance. The multiplexing features of an ASM cluster minimize
the possibility of data loss and are generally more effective than a manual scheme that places
critical files and backups on different physical drives.
Manual Multiplexing
Without a RAID or ASM solution, you can still provide some safeguards for your critical database
files by setting some initialization parameters and providing an additional location for control
files, redo log files, and archived redo log files.
Control Files
Control files can be multiplexed immediately when the database is created, or they can be
multiplexed later with a few extra steps to manually copy them to multiple destinations. You
can multiplex up to eight copies of a control file.
Whether you multiplex the control files when the database is created or you multiplex them
later, the initialization parameter value for CONTROL_FILES is the same.
If you want to add another multiplexed location, you need to edit the initialization parameter
file and add another location to the CONTROL_FILES parameter. If you are using an SPFILE
instead of an init.ora file, then use a command similar to the following to change the CONTROL_
FILES parameter:
alter system
set control_files = '/u01/oracle/whse2/ctrlwhse1.ctl,
/u02/oracle/whse2/ctrlwhse2.
Pages:
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107