Databases Reference
In-Depth Information
Figure 11-3. RAID levels commonly used with an Oracle Database
Automatic Storage Management
Oracle Database versions dating back to Oracle Database 10
g
include Automatic Storage
Management (ASM). We introduced ASM in
Chapter 5
and described its manageability
considerations. ASM enables you to create a pool of storage on disk groups and then
manages the placement of database files on the storage. ASM features enable it to replace
non-Oracle file systems and logical volume managers for files managed by the Oracle
Database. An ASM instance manages each of the disks in the disk group, and one ASM
instance is provided for each database node in a RAC environment.
ASM is an Oracle-recommended MAA solution to handle storage failures and data
corruption. It provides “Striping and Mirroring Everything” (SAME) for many types of
disks, including “Just a Bunch of Disks” (JBOD) arrays. You can specify groups of disks,
and designate a failure group to be used in the result of a disk failure. Mirroring can
also be set up on a per-file basis, and you can specify one mirror (normal redundancy)
or two mirrors (high redundancy). ASM includes the ability to detect disk “hot spots”
and redistribute data to avoid disk bottlenecks, as well as the capability of adding disks
to a disk group without any interruption in service. DBAs add the disks to disk groups
or remove disks from disk groups using Oracle Enterprise Manager.
