Mapping ASM disks to Physical Devices

Sometimes you may need to map ASM Disks to its physical devices. 

If they are based on ASMLib you will see their ASM name, ie: ORCL:VOL1 when querying v$asm_disk

When running oracleasm querydisk VOL1 you will get in addition the major - minor numbers, that can be used to match the physical device, ie:

[root@orcldb2 ~]# /etc/init.d/oracleasm querydisk VOL1
Disk "VOL1" is a valid ASM disk on device [8, 97]

[root@orcldb2 ~]# ls -l /dev | grep 8, | grep 97
brw-rw----   1 root disk     8,      81 Nov  4 13:02 sdg1

This script can do the job for a group of ASM Disks:

---------- start  here ------------
#!/bin/ksh
for i in `/etc/init.d/oracleasm listdisks`
do
v_asmdisk=`/etc/init.d/oracleasm querydisk $i | awk  '{print $2}'`
v_minor=`/etc/init.d/oracleasm querydisk $i | awk -F[ '{print $2}'| awk -F] '{print $1}' | awk '{print $1}'`
v_major=`/etc/init.d/oracleasm querydisk $i | awk -F[ '{print $2}'| awk -F] '{print $1}' | awk '{print $2}'`
v_device=`ls -la /dev | grep $v_minor | grep $v_major | awk '{print $10}'`
echo "ASM disk $v_asmdisk based on /dev/$v_device  [$v_minor $v_major]"
done
---------- finish here ------------

The output looks like this:

ASM disk "VOL1" based on /dev/sdg1  [8, 97]
ASM disk "VOL10" based on /dev/sdp1  [8, 241]
ASM disk "VOL2" based on /dev/sdh1  [8, 113]
ASM disk "VOL3" based on /dev/sdk1  [8, 161]
ASM disk "VOL4" based on /dev/sdi1  [8, 129]
ASM disk "VOL5" based on /dev/sdl1  [8, 177]
ASM disk "VOL6" based on /dev/sdj1  [8, 145]
ASM disk "VOL7" based on /dev/sdn1  [8, 209]
ASM disk "VOL8" based on /dev/sdo1  [8, 225]
ASM disk "VOL9" based on /dev/sdm1  [8, 193]

If you are using multi-path, you will need an additional step to map the physical device to the multi-path device, for instance if using EMC Powerpath if you want to map sdf1

[root@orclp ~]# /etc/init.d/oracleasm querydisk vol1
Disk "VOL1" is a valid ASM disk on device [8, 81]

[root@orclp ~]# ls -l /dev | grep 8,| grep 81
brw-rw----   1 root disk     8,      81 Oct 29 20:42 sdf1

[root@orclp ~]# powermt display dev=all
...
...
Pseudo name=emcpowerg
Symmetrix ID=000290101698
Logical device ID=0214
state=alive; policy=SymmOpt; priority=0; queued-IOs=0
==============================================================================
---------------- Host ---------------   - Stor -   -- I/O Path -  -- Stats ---
### HW Path                 I/O Paths    Interf.   Mode    State  Q-IOs Errors
==============================================================================
   1 qla2xxx                   sdf       FA  7bB   active  alive      0      0
   2 qla2xxx                   sdq       FA 10bB   active  alive      0      0
...
...

The last step is to check the partition assigned to the emcpower device, ie:

[root@orclp ~]# ls -l /dev/emcpowerg*
brw-------  1 root root 120, 96 Oct 29 20:41 /dev/emcpowerg
brw-------  1 root root 120, 97 Nov 15 13:08 /dev/emcpowerg1

Source: https://blogs.oracle.com/AlejandroVargas/entry/mapping_asm_disks_to_physical