Databases Reference
In-Depth Information
Data Recovery Advisor
The Data Recovery Advisor is used in recovering from corrupted blocks, corrupted
or missing files, and other data failures and is integrated with database health checks
and RMAN.
Automatic Storage Management
Part of the Oracle Database since Oracle Database 10
g
, Automatic Storage Management
(ASM) provides a file system and volume manager in the database, enabling automated
striping of files and automating mirroring of database extents. DBAs simply define a
pool of storage or disk group and manage the disk group through EM. Disk groups are
created with normal redundancy as the default (two-way mirroring). You can also create
disk groups with high redundancy (three-way mirroring) or external redundancy (no
mirroring). Failure groups are ASM disks that share a common failure point, so mir‐
roring will automatically occur to a different failure group to provide high availability.
Oracle manages the files that are stored in ASM disk groups. ASM manages Oracle
datafiles, logfiles, control files, archive logs, and RMAN/backup sets. Workloads can be
dynamically rebalanced as storage is reconfigured such that when storage is added or
removed from the pool, data can be redistributed in the background.
Oracle Database 12
c
introduces a number of features that improve the availability and
reliability of ASM. ASM disk scrubbing provides automatic repair of logical data cor‐
ruptions. ASM disk resync allows multiple disks to be brought back online simultane‐
ously.
Oracle Enterprise Manager
Oracle Enterprise Manager was first distributed with Oracle7 and was focused at that
time on just simplifying database management. Early EM versions required Windows-
based workstations as client machines. A Java applet browser-based EM console ap‐
peared with the Oracle8
i
database release. The HTML-based console was introduced
with Oracle9
i
and is now the basis for Enterprise Manager 12
c
used to manage the
database and many other Oracle products and platforms for cloud-based and other
deployments. Alternatively, Enterprise Manager 12
c
can be accessed via iOS devices
including iPhones and iPads.
Oracle Database 12
c
also comes with a small footprint version of Enterprise Manager
called Enterprise Manager Express that requires no additional middleware. Enterprise
Manager Express provides basic storage, security, and configuration administration
support as well as advanced performance diagnostics and tuning.
Enterprise Manager provides a basic interface for monitoring and management of Ora‐
cle Database users and user privileges, database schema and database configuration
