Migrating Oracle Automatic Storage Management (ASM) disk groups on operating system devices to Dynamic Multi-Pathing (DMP) devices


Migrating Oracle Automatic Storage Management (ASM) disk groups on operating system devices to Dynamic Multi-Pathing (DMP) devices
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When an existing ASM disk group uses operating system native devices as disks, you can migrate these devices to Dynamic Multi-Pathing control. If the OS devices are controlled by other multi-pathing drivers, this operation requires system downtime to migrate the devices to DMP control.

Plan for system downtime for the following procedure.

After this procedure, the ASM disk group uses the migrated DMP devices as its disks.

"From ASM" indicates that you perform the step as the user running the ASM instance.

"As root user" indicates that you perform the step as the root user.

To migrate an ASM disk group from operating system devices to DMP devices

Stop the applications and shut down the database.
From ASM, identify the ASM disk group that you want to migrate, and identify the disks under its control.
From ASM, dismount the ASM disk group.
If the devices are controlled by other multi-pathing drivers, migrate the devices to DMP control. Perform these steps as root user.
Migrate from MPIO or PowerPath.
As root user, enable DMP support for the ASM disk group identified in step 2.
```
# vxdmpraw enable username groupname mode [devicename ...]
```
where username represents the ASM user running the ASM instance, groupname represents the UNIX/Linux groupname of the specified user-id, and mode represents the permissions to set on the device. If you specify one or more devicenames, DMP support for ASM is enabled for those devices. If you do not specify a devicename, DMP support is enabled for all devices in the system that have an ASM signature.
From ASM, set ASM_DISKSTRING as appropriate. The preferred setting is /dev/vx/rdmp/*
From ASM, confirm that the devices are available to ASM.
From ASM, mount the ASM disk groups. The disk groups are mounted on DMP devices.

Example: To migrate an ASM disk group from operating system devices to DMP devices

From ASM, identify the ASM disk group that you want to migrate, and identify the disks under its control.

SQL> select name, state from v$asm_diskgroup; 
NAME                           STATE 
------------------------------ ----------- 
ASM_DG1                        MOUNTED

SQL> select name,path,header_status from v$asm_disk; 
NAME		       PATH		            HEADER_STATUS 
------------------------------------------- 
ASM_DG1_0000	/dev/rhdisk43	    MEMBER 
ASM_DG1_0001	/dev/rhdisk51	    MEMBER 
ASM_DG1_0002	/dev/rhdisk97	    MEMBER

From ASM, dismount the ASM disk group.

SQL> alter diskgroup ASM_DG1 dismount; 
Diskgroup altered. 

SQL> select name , state from v$asm_diskgroup; 
NAME                           STATE 
------------------------------ ----------- 
ASM_DG1                        DISMOUNTED

If the devices are controlled by other multi-pathing drivers, migrate the devices to DMP control. Perform these steps as root user.
As root user, enable DMP support for the ASM disk group identified in step 2, in one of the following ways:
- To migrate selected ASM diskgroups, use the vxdmpadm command to determine the DMP nodes that correspond to the OS devices.
```
# vxdmpadm getdmpnode nodename=hdisk4 
NAME       STATE   ENCLR-TYPE PATHS ENBL DSBL ENCLR-NAME 
======================================================== 
EVA4K6K0_0 ENABLED EVA4K6K    4     4    0    EVA4K6K0 
```
  Use the device name in the command below:
```
# vxdmpraw enable oracle dba 660 eva4k6k0_0 \ 
     eva4k6k0_9 emc_clariion0_243
```
- If you do not specify a devicename, DMP support is enabled for all devices in the disk group that have an ASM signature. For example:
```
# vxdmpraw enable oracle dba 660
```

From ASM, set ASM_DISKSTRING.

SQL> alter system set ASM_DISKSTRING='/dev/vx/rdmp/*';
System altered. 	
SQL> show parameter ASM_DISKSTRING; 	
NAME                       TYPE      VALUE 	
-------------------------- --------- -------------------
asm_diskstring             string    /dev/vx/rdmp/*

From ASM, confirm that the devices are available to ASM.

SQL> select path , header_status from v$asm_disk where 
header_status='MEMBER';

NAME	     PATH	                              HEADER_STATUS 
----------------------------------------------------------
          /dev/vx/rdmp/emc_clariion0_243	    MEMBER
          /dev/vx/rdmp/eva4k6k0_9			         MEMBER 		
          /dev/vx/rdmp/eva4k6k0_1			         MEMBER

From ASM, mount the ASM disk groups. The disk groups are mounted on DMP devices.

SQL> alter diskgroup ASM_DG1 mount; 	
Diskgroup altered.
 	
SQL> select name, state from v$asm_diskgroup; 
NAME                           STATE 	
------------------------------ ----------- 	
ASM_DG1                        MOUNTED

SQL>  select name,path,header_status from v$asm_disk where 
header_status='MEMBER'; 
NAME		        PATH								                   HEADER_STATUS 
---------------------------------------------------------- 
ASM_DG1_0002	/dev/vx/rdmp/emc_clariion0_243		MEMBER 
ASM_DG1_0000	/dev/vx/rdmp/eva4k6k0_1				     MEMBER 
ASM_DG1_0001	/dev/vx/rdmp/eva4k6k0_9	        MEMBER

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