This blog contains the list of useful asmcmd commands which are important in your day to day operations.
List all diskgroups:
ASMCMD> lsdg
-- Include dismounted diskgroups:
ASMCMD> lsdg --discovery
-- List diskgroups across all nodes of cluster:
ASMCMD> lsdg -g --discovery
2. List asm disks:
a.List all asm disks
ASMCMD> lsdsk -k
b. List disks of a diskgroup(CDATA) with free and total MB
ASMCMD> lsdsk -k -G CDATA
c. List disks of a diskgroup(CDATA) with group and disk number
ASMCMD> lsdsk -p -G CDATA
d. List disks with disk creation date
ASMCMD> lsdsk -t -G CDATA
e. List candidiate disks only
ASMCMD> lsdsk --candidate -k
f. List member disks only
ASMCMD> lsdsk --candidate -p
 3. Get attributes of ASM diskgroups:
a. List attribute of all diskgroups:
ASMCMD> lsattr -lm
b. List attribute of specific diskgroup(DMARCH)
ASMCMD> lsattr -lm -G DMARCH
Group_Name Name Value RO Sys
DMARCH access_control.enabled FALSE N Y
DMARCH access_control.umask 066 N Y
DMARCH au_size 1048576 Y Y
DMARCH cell.smart_scan_capable FALSE N N
c. List attributes with specific pattern
ASMCMD> lsattr -lm %au_size%
 4. Unmount diskgroup:
unmount command works only on the local node. So if you want to unmount the diskgroup from all nodes of cluster, then run this command from all the nodes.
a. unmount all diskgroups
ASMCMD> umount -a
b. unmount specific diskgroup(ARCH)
ASMCMD> umount ARCH
5. Mount diskgroup:
Mount command works only on the local node. So if you want to Mount the diskgroup from all nodes of cluster, then run this command from all the nodes.
a. mount all diskgroups on local node
ASMCMD> mount -a
b. mount a specific diskgroup on local node
ASMCMD> mount ARCH
6. Rebalance a diskgroup:
a. here asm_power_limit is 8 and diskgroup is ARCH
ASMCMD> rebal --power 8 ARCH
Rebal on progress.
b. Monitor progress
ASMCMD> lsop