Oracle RAC ASM Multi-Disk Online Method

Performing encryption with the online rebalancing method requires sufficient free space to allow the drop of the largest ASM disk.

Checking for Space

In the Oracle system, use the following commands to check for available disk space:

1. Check total free space in the disk group:

   SELECT name, free_mb, total_mb, free_mb/total_mb*100 as percentage FROM v$asm_diskgroup;
   
   NAME                              FREE_MB   TOTAL_MB PERCENTAGE
   ------------------------------ ---------- ---------- ----------
   DATA                                    7       2109 .331910858

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2. Check individual ASM disk size and usage:

   select a.name DiskGroup, b.disk_number Disk#, b.name DiskName, b.total_mb, b.free_mb, b.path, b.header_status FROM v$asm_disk b, v$asm_diskgroup a where a.group_number (+) =b.group_number order by b.group_number, b.disk_number, b.name
   
   DISKGROUP  DISK#  DISKNAME        TOTAL_MB    FREE_MB   PATH                            HEADER_STATUS
   ---------  -----  --------       ---------    -------   ------------------------------  -------------
   DATA        0     DATA_0000           1874       1273   /dev/oracleasm/disks/DATA3      MEMBER
   DATA        1     DATA_0001           1992        608   /dev/oracleasm/disks/DATA4      MEMBER
   DATA        3     DATA_0003            117          0   /dev/oracleasm/disks/DATA2      MEMBER
               0     DATA_ENC_0000        109         28   /dev/oracleasm/disks/DATA1_ENC  MEMBER

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Adding a Disk to the Diskgroup

Using the Online Method assumes that there is enough free space in the diskgroup so that you can drop/remove a disk, protect it with CTE, and then add it back into the diskgroup.

To add the disk to the diskgroup:

1. Open a terminal session on both RAC Nodes.

2. On RAC Node 1, on the ASM, remove the disk from the disk group, type.

   ALTER DISKGROUP <diskGroupName> DROP DISK <diskName> REBALANCE POWER 11 WAIT;

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3. On the CipherTrust Manager, in the Host Group, apply a GuardPoint to the Raw Device: <rawDevice1Name>.

4. From RAC Node 1, to display the status of the guarded disks, type:

   secfsd -status guard

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5. On both RAC Node 1 and 2 type:

   chown oracle:oinstall /dev/secvm/<rawDevice1Name>
   chmod 660 /dev/secvm/<rawDevice1Name>

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6. From RAC Node, on the ASM, add the protected disk to the disk group:

   ALTER DISKGROUP <diskGroupName> ADD DISK /dev/secvm/<rawDevice1Name> NAME <disk1Name>;

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   The disk is now added to the diskgroup and ready for use.

7. The system is now ready for a reboot and failover test. For details, see Surviving the Reboot and Failover Testing.

Troubleshooting

Occasionally, settings do not persist when the system is rebooted. To ensure they do persist, edit the /etc/rc.local file and add the following lines:

Echo “Changing Permission for secvm devices”
chown oracle:oinstall /dev/secvm/dev/<rawDevice1Name>
chmod 660 /dev/secvm/dev/<rawDevice1Name>