OCP-1Z0-053-200题-104题-235

QUESTION 104

The ORACLE_SID environment variable is set to +ASM. ASMLIB is not used in the configuration. You

executed the following command to startup the Automatic Storage Management (ASM) instance.

SQL> STARTUP;

Which two activities are performed during a successful start up operation? (Choose two.)

A. The databases configured to use the ASM instance aremounted

B. The disk groups are mounted as per the ASM_DISKGROUPS initialization parameter

C. ASM starts the Oracle Cluster Synchronization Services (CSS) daemon if it is not started

D. ASM discovers and examines the contents of all files that are in the paths specified in the

ASM_DISKGROUPS initialization parameters

Answer: BC

同235题：http://blog.csdn.net/rlhua/article/details/13008361

Explanation/Reference:

Section: Database Architecture & Resource Management, RAC, ASM

There is only 1 good answer.. D would be correct ifASM_DISKGROUPS is replaced with ASM_DISKSTRING

ASM does not start CSS it may prompt user to run local config add to start CSS service.

http://download.oracle.com/docs/cd/B14117_01/server.101/b10739/storeman.htm#i1013975

Starting Up an ASM Instance

ASM instances are started similarly to Oracle database instances with some minor differences. These are:

- The initialization parameter file, which can be a server parameter file, must contain:

INSTANCE_TYPE = ASM

- This parameter signals the Oracle executable that an ASM instance is starting and not a

database instance.

- Using a server parameter file is recommended because it eliminates the need to make manual

changes to a text initialization parameter file.

- For ASM instances, STARTUP tries to mount the disk groups specified by the initialization

parameter ASM_DISKGROUPS and not the database.

Further, the SQL*Plus STARTUP command parameters are interpreted by Automatic Storage Management as

follows:

The following is a sample SQL*Plus session where an ASMinstance is started:

% sqlplus /nolog

SQL> CONNECT / AS sysdba

Connected to an idle instance.

SQL> STARTUP

ASM instance started

Total System Global Area 147936196 bytes

Fixed Size 324548 bytes

Variable Size 96468992 bytes

Database Buffers 50331648 bytes

Redo Buffers 811008 bytes

ASM diskgroups mounted

ASM Instance Memory Requirements

ASM instances are smaller than database instances. A 64 MB SGA should be sufficient for all but the largest

ASM installations.

Disk Discovery

When an ASM instance initializes, ASM is able to discover and look at the contents of all of the disks in the

disk groups that are pointed to by the ASM_DISKSTRING initialization parameter. This saves you from having

to specify a path for each of the disks in the diskgroup.

Disk group mounting requires that an ASM instance doing disk discovery be able to access all the disks within

the disk group that any other ASM instance having previously mounted the disk group believes are membersof

that disk group. It is vital that any disk configuration errors be detected before a disk group is mounted.

Automatic Storage Management attempts to identify the following configuration errors:

A single disk with different mount points is presented to an ASM instance. This can be caused by multiple

paths to a single disk. In this case, if the disk in question is part of a disk group, disk group mount fails. If the

disk is being added to a disk group with ADD DISK or CREATE DISKGROUP, the command fails. To correct

the error, restrict the disk string so that it doesnot include multiple paths to the same disk.

Multiple ASM disks, with the same ASM label, passed to separate ASM instances as the same disk. In this

case, disk group mount fails.

Disks that were not intended to be ASM disks are passed to an ASM instance by the discovery function. ASM

does not overwrite a disk if it recognizes the header as that of an Oracle object.

Disk Group Recovery

When an ASM instance fails, then all Oracle database instances on the same node as that ASM instance and

that use a disk group managed by that ASM instance also fail. In a single ASM instance configuration, if the

ASM instance fails while ASM metadata is open for update, then after the ASM instance reinitializes, it reads

the disk group log and recovers all transient changes.

With multiple ASM instances sharing disk groups, if one ASM instance should fail, another ASM instance

automatically recovers transient ASM metadata changescaused by the failed instance. The failure of an

Oracle database instance is not significant here because only ASM instances update ASM metadata.