Check ASM disk group layout ASMCMD> lsdg State Type Rebal Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files Name MOUNTED NORMAL N 512 4096 1048576 20456 12878 5114 3882 0 Y DATA/ Check space for a certain directory ASMCMD> du _MGMTDB/ Used_MB Mirror_used_MB 3407 6838 Check ASM disk usage: ASMCMD> lsdsk -k Total_MB Free_MB OS_MB Name Failgroup Failgroup_Type Library Label UDID Product Redund Path 5114 3212 5114 DATA_0000 DATA_0000 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA1 5114 3207 5114 DATA_0001 DATA_0001 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA2 5114 3216 5114 DATA_0002 DATA_0002 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA3 5114 3243 5114 DATA_0003 DATA_0003 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA4 Drop disk 5 GByte DATA_0003 and create 2 new disks DATA_0003 and DATA_0004 with 10GByte each Drop disk delete ASMlib entry SQL> alter diskgroup data drop disk DATA_0003; Diskgroup altered. Now run on grac121 and grac122 # /etc/init.d/oracleasm deletedisk DATA4 Removing ASM disk "DATA4": [ OK ] # /etc/init.d/oracleasm listdisks DATA1 DATA2 DATA3 Create ASM disks format and add them to our DATA diskgroup $ /etc/init.d/oracleasm createdisk data1 /dev/sde1 Marking disk "data1" as an ASM disk: [ OK ] $ /etc/init.d/oracleasm createdisk data1 /dev/sdf1 Marking disk "data1" as an ASM disk: [ OK ] Use asmca and add the disk to our disk DATA disk group . Verify the new disk group layout $ asmcmd lsdsk -k Total_MB Free_MB OS_MB Name Failgroup Failgroup_Type Library Label UDID Product Redund Path 5114 2112 5114 DATA_0000 DATA_0000 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA1 10236 9444 10236 DATA_0003 DATA_0003 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA10G_1 10236 9475 10236 DATA_0004 DATA_0004 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA10G_2 5114 2113 5114 DATA_0001 DATA_0001 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA2 5114 5111 5114 DATA_0002 DATA_0002 REGULAR System UNKNOWN /dev/oracleasm/disks/DATA3 $ asmcmd lsdg State Type Rebal Sector Block AU Total_MB Free_MB Req_mir_free_MB Usable_file_MB Offline_disks Voting_files Name MOUNTED NORMAL Y 512 4096 1048576 30700 23140 10236 6452 0 Y DATA/ $ /etc/init.d/oracleasm listdisks DATA1 DATA10G_1 DATA10G_2 DATA2 DATA3