Database Reference
In-Depth Information
Node1
Node2
Node3
Database
Instance
Grid Infrastructure
Database
Instance
Grid Infrastructure
Database
Instance
Grid Infrastructure
ASM
Instance
ASM
Instance
ASM
Instance
Clusterware
Clusterware
Clusterware
Node4
Node5
Database
Instance
Grid Infrastructure
SharedStorage
Grid Infrastructure
Clusterware
Clusterware
Figure 5-8.
Dependency on Oracle 12c Flex ASM
Creation and Ownership of ASM Instance
However, the relationship between the ASM instance and Oracle Clusterware has been changed from Oracle 11g R1
to Oracle 11gR2/12cR1. The ASM instance depends on Oracle Clusterware for the basic cluster infrastructure and
the communication between the cluster nodes. The 11gR1 Oracle Clusterware doesn't rely on the ASM instance to
access the OCR and voting disk files, as these two important components for the Clusterware metadata are directly
stored in block devices. In 11gR1, the ASM instance is created with the DBCA tool after the Oracle Clusterware
installation and before database creation. However in 11gR2 and 12cR1, if you chose to store OCR and voting disks
in ASM, Oracle Clusterware depends on the ASM instance to access the OCR and voting disk. This leads to mutual
dependency between Oracle Clusterware and Oracle ASM. The solution to this dependency is that these two
products are combined together into one product, Grid Infrastructure, and they are installed together into a single
Grid Infrastructure home by the Grid Infrastructure installer. The installation process also creates the ASM instance,
creates the diskgroup for storing OCR and voting disk, and finishes the Oracle Clusterware configuration on all the
RAC nodes in the end.
In a RAC Database environment, the default ASM instance SID is +ASM node_number, such as +ASM1 for node 1
and +ASM2 for node 2, etc. Like an Oracle Database instance, an ASM instance has a set of background processes. For
example, the following is a list of processes of an Oracle 12cR1 ASM instance:
$ps -ef | grep -v grep | grep asm_
grid 4335 1 0 Feb19 ? 00:06:51 asm_pmon_+ASM1
grid 4337 1 0 Feb19 ? 00:05:08 asm_psp0_+ASM1
grid 4339 1 2 Feb19 ? 07:47:18 asm_vktm_+ASM1
grid 4343 1 0 Feb19 ? 00:01:48 asm_gen0_+ASM1
grid 4345 1 0 Feb19 ? 00:00:43 asm_mman_+ASM1
grid 4349 1 0 Feb19 ? 00:18:12 asm_diag_+ASM1
grid 4351 1 0 Feb19 ? 00:03:18 asm_ping_+ASM1
grid 4353 1 0 Feb19 ? 01:12:41 asm_dia0_+ASM1
grid 4355 1 0 Feb19 ? 00:48:21 asm_lmon_+ASM1
grid 4357 1 0 Feb19 ? 00:27:40 asm_lmd0_+ASM1
grid 4359 1 0 Feb19 ? 01:00:51 asm_lms0_+ASM1
grid 4363 1 0 Feb19 ? 00:13:18 asm_lmhb_+ASM1
