Degraded write performance
must be taken into account. Popular
for reads where adequate I/O
is provided. Write penalties may
slow loads and index builds.
Often avoided for high-volume
OLTP due to write penalties.
Some storage vendors, such as
EMC, have proprietary solutions
(RAID-S) to minimize parity overhead
on writes.
Protecting Against System Failure | 265
Figure 11-3 illustrates the disk configurations for various RAID levels.
Automatic Storage Management
Oracle Database 10g and more recent database releases include Automatic Storage
Management (ASM). We introduced ASM in Chapter 5 and described its manageability
considerations. ASM enables youto 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.
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