I was experiencing problems with loosing "oracle:dba" permissions after Linux reboot. It came up with "root:disk" .
Run as root:-
# /sbin/service rawdevices restart
Tune /etc/sysctl.conf,/etc/security/limits.conf,/etc/pam.d/login, /etc/profile.
and oracle's shell environment as advised in .
Login as oracle:-
$ cd /tmp/database
Select " Advanced installation" and
create ASM instance with $ORACLE_HOME=/u01/app/oracle/oracle/product/10.2.0/db_1
During this run create disk group RAWDATA1 with normal redundancy mirroring /dev/raw/raw1 and /dev/raw/raw2
You should be fine with discovering raw devices if permissions are in place (oracle:dba)
Export ORACLE_HOME for ASM instance and corresponding PATH.
Then run "dbca" to create disk group RAWDATA2 with
normal redundancy mirroring /dev/raw/raw3 and /dev/raw/raw4
Select " Advanced installation" and create new ASM-database placed RAWDATA1 diskgroup
with $ORACLE_HOME=/u01/app/oracle/oracle/product/10.2.0/db_2 .
Modify ~oracle/.bash_profile correspondently.Relogin as oracle.
$ sqlplus /nolog
SQL> conn / as sysdba
SQL> shutdown immediate;
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 285212672 bytes
Fixed Size 1218968 bytes
Variable Size 88082024 bytes
Database Buffers 188743680 bytes
Redo Buffers 7168000 bytes
SQL> alter database archivelog;
SQL> alter database rawdbs flashback on;
SQL> alter database open;
Open Enterpise Manager console.(Enterprise Manager 10g Database Control URL http://ServerCentOS41:1158/em). Put flashback recovery area in RAWDATA2 modifying corresponding value on Recovery Settings page of EM.
For Oracle 10g Release 2 in RHEL 4 it is not recommended to use raw devices but to use block devices instead. Raw I/O is still available in RHEL 4 but it is now a deprecated interface. In fact, raw I/O has been deprecated by the Linux community. It has been replaced by the O_DIRECT flag which can be used for opening block devices to bypass the OS cache. Unfortunately, Oracle Clusterware R2 OUI still requires raw devices or a Cluster File System.
By default, reading and writing to block devices are buffered I/Os. Oracle 10g R2 now automatically opens all block devices such as SCSI disks using the O_DIRECT flag, thus bypassing the OS cache. For example, when you create disk groups for ASM and you want to use the SCSI block devices /dev/sdb and /dev/sdc, you can simply set the Disk Discovery Path to "/dev/sdb, /dev/sdc" to create the ASM disk group. There is no need to create raw devices and to point the Disk Discovery Path to it.