Administering Oracle Flex ASM

Oracle Flex ASM is managed by ASMCA, CRSCTL, SQL*Plus, and SRVCTL. The INSTANCE_TYPE initialization parameter specifies the type of instance.

The INSTANCE_TYPE initialization parameter has an additional value ASMPROXY, in addition to ASM and RDBMS, to identify Oracle ASM proxy instances. An Oracle ASM proxy instance has its parameter set to ASMPROXY.

You can use the ASMCMD showclustermode command to determine whether Oracle Flex ASM is enabled. For example:

$ asmcmd showclustermode
ASM cluster : Flex mode enabled

SRVCTL is extended to enable an administrator to create or change attributes of Oracle Clusterware resources. You can use SRVCTL to determine the status of the instances in an Oracle Flex ASM configuration. For example:

$ srvctl status asm -detail
ASM is running on mynoden02,mynoden01
ASM is enabled.

You can also use SRVCTL to determine whether Oracle Flex ASM is enabled. If enabled, then srvctl config asm displays the number of Oracle ASM instances that has been specified for use with the Oracle Flex ASM configuration. For example:

$ srvctl config asm
ASM instance count: 3

You can modify the Oracle ASM instance count, or cardinality, with the SRVCTL modify asm command. For example:

$ srvctl modify asm -count 4

$ srvctl modify asm -count ALL

You can view Oracle Flex ASM connections with SQL*Plus and ASMCMD commands. Fore example:

SQL> SELECT instance_name, db_name, status FROM V$ASM_CLIENT;
INSTANCE_NAME   DB_NAME  STATUS
--------------- -------- ------------
+ASM1           +ASM     CONNECTED
orcl1           orcl     CONNECTED
orcl2           orcl     CONNECTED

$ asmcmd lsct data
DB_Name  Status    Software_Version  Compatible_version  Instance_Name  Disk_Group
+ASM     CONNECTED       12.1.0.0.2          12.1.0.0.2  +ASM           DATA
orcl     CONNECTED       12.1.0.0.2          12.0.0.0.0  orcl1          DATA
orcl     CONNECTED       12.1.0.0.2          12.0.0.0.0  orcl2          DATA

Clients are automatically relocated to another instance if an Oracle ASM instance fails. If necessary, clients can be manually relocated using the ALTER SYSTEM RELOCATE CLIENT command. For example:

SQL> ALTER SYSTEM RELOCATE CLIENT 'client-id';

In the previous SQL statement, client-id is of the form instance_name:db_name. The INSTANCE_NAME and DB_NAME columns are contained in the V$ASM_CLIENT view. You must connect as SYSASM to the Oracle ASM instance to run the SQL statement. When you issue this statement, the connection to the client is terminated and the client fails over to the least loaded instance. If the client is currently connected to the least loaded instance, then the connection to the client is terminated and the client fails over to that same instance.

Every database user must have a wallet with credentials to connect to Oracle ASM. CRSCTL commands can be used by the database user to manage this wallet. All Oracle ASM user names and passwords are system generated.

There are no new initialization parameters specifically for instances in an Oracle Flex ASM configuration; however, the settings of existing parameters should be reviewed and possibly adjusted for the Oracle Flex ASM environment. Refer to "Recommended Settings for Oracle ASM Initialization Parameters".

See Also: