In Linux, ASMLib provides the wrapper for managing the ASM disks. To identify the underlying physical device that the ASM disk point to, you can use the oracleasm querydisk command.
The querydisk option will list the major and minor numbers that can be used to match the physical device.
The following example was run on a virtual server hosting ASM and an Oracle database.
[root@oraclevm ~]# oracleasm listdisks
DATA1
[root@oraclevm ~]# oracleasm querydisk -d DATA1
Disk "DATA1" is a valid ASM disk on device [8,17]
[root@oraclevm ~]# ls -ltr /dev/sd*
brw-rw----. 1 root disk 8, 0 Dec 14 18:18 /dev/sda
brw-rw----. 1 root disk 8, 2 Dec 14 18:18 /dev/sda2
brw-rw----. 1 root disk 8, 1 Dec 14 18:18 /dev/sda1
brw-rw----. 1 root disk 8, 16 Dec 14 18:18 /dev/sdb
brw-rw----. 1 root disk 8, 17 Dec 14 18:18 /dev/sdb1
[root@oraclevm ~]#
In the above example, DATA1 disk is pointing to the /dev/sdb1. The major 8 is block based and refers to SCSI disk devices type.
