The configuration file contains many configuration variables. The ORACLEASM_SCANORDER variable specifies disks to be scanned first.
The ORACLEASM_SCANEXCLUDE variable specifies the disks that are to be ignored.The variables take a whitespace-seperated list of prefix strings to match. In other words, if a disk starts with one of the prefix strings, it matches. For example, the prefix string sd will match all SCSI devices. The disk sda starts with sd. Note that these are not globs. They do not use wildcards. They are simple prefixes. Also note that the /dev/ path is not part of the prefix.
# ORACLEASM_SCANORDER: Matching patterns to order disk scanning
#ORACLEASM_SCANORDER=${ORACLEASM_SCANORDER}ORACLEASM_SCANORDER=emcpowera
# ORACLEASM_SCANEXCLUDE: Matching patterns to exclude disks from scan
#ORACLEASM_SCANEXCLUDE=${ORACLEASM_SCANEXCLUDE}ORACLEASM_SCANEXCLUDE="sda sdb sdc sdd"
more on metalink note 309815.1
Useful metalink notes
Configuring Oracle ASMLib on Multipath Disks [ID 309815.1]
How to Partition DM-Multipath Pseudo Devices [ID 470913.1]
Configuring Oracle ASMLib on Multipath Disks [ID 309815.1]
How To Setup ASM & ASMLIB On Native Linux Multipath Mapper disks? [ID 602952.1]
Configuring non-raw multipath devices for Oracle Clusterware 11g (11.1.0, 11.2.0) on RHEL5/OL5 [ID 605828.1]
Configuring raw devices (multipath) for Oracle Clusterware 10g Release 2 (10.2.0) on RHEL5/OEL5 [ID 564580.1]
How to Configure LUNs for ASM Disks using WWID, DM-Multipathing, and ASMLIB on RHEL 5/OEL 5 [ID 1365511.1]