Application Notes Device Mapper Multipath with Oracle ASM on Linux (5697-7806, April 2009)

Fix permissions of Oracle ASM disks on boot (y/n) [y]:y

Writing Oracle ASM library driver configuration:[ OK ]

Scanning system for ASM disks:[ OK ]

ASMLib on startup scans the devices available on the system and discovers ASMLib labeled disks. Edit

the ASMLib conﬁguration ﬁle /etc/sysconfig/oracleasm as below to scan only DM multipath

devices and exclude u nderlying sd devices:

# ORACLEASM_SCANORDER: Matching patterns to order disk scanning

ORACLEASM_SCANORDER=”mapper/*”

# ORACLEASM_SCANEXCLUDE: Matching patterns to exclude disks from scan

ORACLEASM_SCANEXCLUDE=”sd”

Making disks available to ASMLib

ASMrequiresuniquedeviceforeachdisk. TomakethedisksavailabletoASMLib,completethe

following ste

ps:

1. Select the multipath devices to be associated under ASM management.

2. Mark the selected devices to be used by ASMLib and run the following command as superuser:

# /etc/init.d/oracleasm createdisk <DISK_NAME> <device_name>, where

DISK_NAME ca

n be any valid string and device_name is the multipath device.

Example:

# /etc/init.d/oracleasm createdisk VOL1 /dev/mapper/mpath1p1

Marking disk “

/dev/mapper/mpath1p1” as an ASM disk:[ OK ]

3. Scan the marked devices by running the following command:

# /etc/init.d/oracleasm scandisks

To verify that ASMLib has marked the disks, run the following command:

# /etc/init.d/oracleasm listdisks

Conﬁguring ASM

While conﬁguring ASM, the conﬁgured ASM disks will be listed as candidate disks. Select each of the

disks to be included in the d isk group and complete the installation.

After installing an ASM instance, perform the ﬁnal ASM conﬁguration. When ASMLib and DM based

paths are used, the ASM initialization parameter asm_diskstring must be speciﬁed as ORCL:*.This

parameter speciﬁes a comma-delimited list of strings that limits the set of disks that an ASM instance

discovers. Using a more restrictive value may reduce the time required for ASM to perform discovery, and

thus improve disk group mount time or the time for adding a disk to a disk group.

Troubleshooting a nd recovery

All path failed condition

When all the paths to the DM devices fail, the database becomes inaccessible. Once the paths are

recovered, the ASM disks need to b e rem ounted using the following steps:

1. Run the following command:

oracle@foo> $ORACLE_HOME/bin/dbca

The following screen displays:

Device Mapper Multipath with Oracle ASM on Linux