How to check the disk utilization where ASMLIB is configured

Get the list all physical disk that are mapped to ASM disk by using following shell script,

[root@todbex01 mp]# cat asm_to_dik.sh#!/bin/bash
for asmlibdisk in `ls /dev/oracleasm/disks/*`
  do
    echo "ASMLIB disk name: $asmlibdisk"
    asmdisk=`kfed read $asmlibdisk | grep dskname | tr -s ' '| cut -f2 -d' '`
    echo "ASM disk name: $asmdisk"
    majorminor=`ls -l $asmlibdisk | tr -s ' ' | cut -f5,6 -d' '`
    device=`ls -l /dev | tr -s ' ' | grep -w "$majorminor" | cut -f10 -d' '`
    echo "Device path: /dev/$device"
  done

[root@todbex01 mp]# sh asm_to_dik.sh
ASMLIB disk name: /dev/oracleasm/disks/COR01
ASM disk name: OCR_VOTE_0000
Device path: /dev/dm-40
ASMLIB disk name: /dev/oracleasm/disks/COR02
ASM disk name: OCR_VOTE_0001
Device path: /dev/dm-37
ASMLIB disk name: /dev/oracleasm/disks/COR03
ASM disk name: OCR_VOTE_0002
Device path: /dev/dm-34
ASMLIB disk name: /dev/oracleasm/disks/DATA01
ASM disk name: ORADATA_0000
Device path: /dev/dm-24

You can get the same result by using oracleasm utility too,

[root@todbex01 mp]# /usr/sbin/oracleasm querydisk -v DATA01
Disk "DATA01" is a valid ASM disk
[root@todbex01 mp]# /usr/sbin/oracleasm querydisk -v -d DATA01
Disk "DATA01" is a valid ASM disk on device [252,24]
[root@todbex01 mp]# ls -l /dev | grep 252,|grep 24
brw-rw----  1 root root     252,  24 May 26  2015 dm-24
[root@todbex01 mp]#

Once you find out the physical disk associated with your diskgroup you can make use of iostat to get the I/O statistics for that particular disk .

Some information about iostat:-

iostat - Report Central Processing Unit (CPU) statistics and input/output statistics for devices and partitions.

Commonly used option:-
-c     The -c option is exclusive of the -d option and displays only the CPU usage report.

        that is iostat option -c, displays only the CPU usage statistics as shown below.
-d     The -d option is exclusive of the -c option and displays only the device utilization report.
-k    Display statistics in kilobytes per second instead of blocks per second. 

-m   Display statistics in megabyte per second instead of blocks per second.  

-n    Displays only the device and NFS statistics.
-x     Display  extended statistics.

Eg,
       iostat -d 2
              Display a continuous device report at two second intervals.(until you press Ctl-C).
       iostat -d 2 6
              Display six reports at two second intervals for all devices.

       iostat -x hda hdb 2 6
              Display six reports of extended statistics at two second intervals for devices hda and hdb.

       iostat -p sda 2 6
              Display six reports at two second intervals for device sda and all its partitions (sda1, etc.)

   
[root@todbex01 mp]#iostat -dkx /dev/dm-24
Linux 2.6.39-400.214.4.el5uek (todbex01)       03/02/2016

Device:         rrqm/s   wrqm/s   r/s   w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util
dm-24             0.00     0.00 174.69  9.00 16721.00    41.19   182.50     0.16    0.88   0.12   2.20

The main figure that we have consider is the %util field,

%util: When this figure is consistently approaching above 80% you will need to take any of the following actions -

    increasing RAM so dependence on disk reduces
    increasing RAID controller cache so disk dependence decreases
    increasing number of disks so disk throughput increases (more spindles working parallely)

[root@todbex01 mp]#

To get the input/output statistics for all disks at two second intervals use the following command

[root@todbex01 mp]#iostat -dkx 2