White Paper

Oracle Database Migration to Dell PowerEdge 12

Generation Servers and Dell Compellent Storage

Systems

database. This method is typically faster than the export and import utility by avoiding extracting

data and instead directly integrating datafiles into the target database. However, an extended

downtime for large databases can still occur.

 Oracle Golden Gate software provides real-time data replication between Oracle databases.

Golden Gate software enables the capability to migrate Oracle database with zero database

downtime and minimal application switchover downtime. Golden Gate software is licensed

separately from Oracle databases.

 Compellent Thin Import is an array-based data migration tool provided by the Dell Compellent

storage systems. Thin Import migrates data from external storage systems to thin-provisioned

volumes on the Compellent system. This helps eliminate the allocated but unused space in the

source data, and deliver more usable capacity on the Compellent system. Thin Import is primarily

an offline activity that incurs database downtime.

Oracle Automatic Storage Management (ASM) Disk Rebalance

Oracle ASM is a volume manager and a file system for Oracle database files that supports single-

instance Oracle database and Oracle RAC configurations. Oracle ASM is Oracle’s recommended storage

management solution, which provides an alternative to conventional volume managers, file systems,

and raw devices. Oracle ASM uses disk groups to store data files. Oracle ASM disk group is a collection

of disks that Oracle ASM manages as a unit. Within a disk group, Oracle ASM exposes a file system

interface for Oracle database files. The content of files that are stored in a disk group is evenly

distributed to eliminate hot spots and to provide uniform performance across the disks. The

performance is comparable to the performance of raw devices.

Oracle ASM provides the disk rebalance feature where disks can be added or removed from a disk group

while a database continues to access files from the disk group. When adding or removing disks from a

disk group, Oracle ASM automatically redistributes the file contents and eliminates the need for

downtime when redistributing the content. The adding or removing disks from a disk group can be

executed using the ALTER DISKGROUP SQL statement within the ASM instance. To control the speed

and resource consumption of the rebalance operation, you can include the REBALANCE POWER clause

in the ALTER DISKGROUP statement. The REBALANCE POWER clause specifies the degree of

parallelism, and thus the speed of the rebalance operation. It can be set to a value from 0 to 11 for

Oracle database versions 11.2.0.2 or lower. A value of 0 halts a rebalancing operation. The default

rebalance power is set by the ASM_POWER_LIMIT initialization parameter with a default value of 1.

The SQL syntax to add disks into a disk group is:

alter diskgroup diskgroup_name

add disk ‘disk_path’

rebalance power n;

For example,

SQL> alter diskgroup data

add disk '/dev/mapper/data1p1'

rebalance power 0;

The SQL syntax to drop disks into a disk group is: