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We're running Oracle with a two node RAC and our FRA diskgroup is running low on space. I need to allocate some more disks to it through ASM. I'm not sure how to go about doing this. I can login to a node and get to asmcmd or other asm command line utilities. What do I need to do?

EDIT: Didn't know it was relevant till Phil's answer: we're using raw disk devices.

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up vote 6 down vote accepted

This assumes that you've already partitioned the presented disk(s) (and will be using /dev/sd[whatever]N), and that you're using asmlib. There will be a kernel module loaded if you are:

[root@oel61 disks]# lsmod | grep oracle
oracleasm              53865  1 
[root@oel61 disks]# 

As root, scan for candidate disks:

[root@oel61 ~]# /etc/init.d/oracleasm scandisks
Scanning the system for Oracle ASMLib disks:               [  OK  ]
[root@oel61 ~]#

Then, check to see if the disk has already been "discovered" by ASM:

oracle@oel61 ~]$ asmcmd -p
ASMCMD [+] > lsdsk
ASMCMD [+] >

If not, we need to stamp the device:

[root@oel61 ~]# /etc/init.d/oracleasm createdisk NEWFRA /dev/sdc1
Marking disk "NEWFRA" as an ASM disk:                       [  OK  ]
[root@oel61 ~]#

Scan for candidate disks again, then list - the new device should be there:

[root@oel61 ~]# /etc/init.d/oracleasm scandisks
Scanning the system for Oracle ASMLib disks:               [  OK  ]
[root@oel61 ~]#

# /etc/init.d/oracleasm listdisks

Or use asmcmd:

oracle@oel61 ~]$ asmcmd -p
ASMCMD [+] > lsdsk
ASMCMD [+] >

Now do a scandisks on the other node and check that everything is as it is on the first node (should be fine if you're using the same /dev device names).

Now the disk is ready to be added to the group.

List the groups:

[oracle@oel61 ~]$ export ORACLE_SID="+ASM"
[oracle@oel61 ~]$ sqlplus / as sysdba

SQL*Plus: Release Production on Thu Jan 31 15:35:27 2013

Copyright (c) 1982, 2010, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release - 64bit Production
With the Automatic Storage Management option

SQL> select name
  2  from V$ASM_DISKGROUP;



Add disk to the group:

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Somewhat helpful so +1. Didn't know the fact we were using raw was relevant. – rfusca Jan 31 '13 at 15:48

Hint: If you're adding more than one disk it's good practice to add an option:


When you add a new disk Oracle will start new background rebalancing process. If you add another disk it can be confused. So it is safer to add disks with rebalance power of 0. And then add the last one using default rebalance power.

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