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  1. #1
    Join Date
    Aug 2005

    Oracle's 10gR2 ASM with Standard Linux I/O in CentOS 4.1 environment

    View also:-


    This method creates Oracle database files on raw character devices
    managed by ASM using standard Linux I/O system calls.It requires to create RAW devices for all disk partitions used by ASM.

    1.Install CentOS 4.1
    2.Run as root:

    # groupadd dba # group of users to be granted SYSDBA system privilege
    # groupadd oinstall # group owner of Oracle files
    # useradd -c "Oracle software owner" -g oinstall -G dba oracle
    # passwd oracle
    # mkdir -p /u01/app/oracle
    # chown -R oracle.oinstall /u01
    # mkdir -p /u02/oradata/data
    # chown -R oracle.oinstall /u02

    Just as an example create 4 partitions:

    /dev/hda6,/dev/hdc6 5 GB each one
    /dev/hda7,/dev/hdc7 3 GB each one

    Create raw devices modifying file /etc/sysconfig/rawdevices as follows:

    /dev/raw/raw1 /dev/hda6
    /dev/raw/raw2 /dev/hdc6
    /dev/raw/raw3 /dev/hda7
    /dev/raw/raw4 /dev/hdc7

    Put in /etc/rc.d/rc.local

    chown oracle:dba /dev/raw/raw*
    chmod 660 /dev/raw/raw*

    I was experiencing problems with loosing "oracle:dba" permissions after Linux reboot. It came up with "root:disk" .

    Restart Linux

    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 [1].
    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)

    Exit installer.

    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

    $ ./runInstaller

    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;
    Database closed.
    Database dismounted.
    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
    Database mounted.
    SQL> alter database archivelog;
    Database altered.
    SQL> alter database rawdbs flashback on;
    Database altered.
    SQL> alter database open;
    Database altered.

    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.

    Last edited by dbaxps; 11-19-2005 at 07:54 AM.

  2. #2
    Join Date
    Aug 2005

    Using Block Devices for Oracle 10g Release 2 in RHEL 4

    PLease, view:-


    Per Werner Puschitz:-

    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.
    Last edited by dbaxps; 07-03-2006 at 07:56 AM.

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