??? Use RAID-5 for database files, provided that the write overhead is acceptable
and adequate I/O is available.
??? Use RAID-1 or RAID-0+1 for database files if RAID-5 write overhead is
unacceptable.
264 | Chapter 11: Oracle and High Availability
Table 11-2. RAID levels relevant to high availability
Level Disk configuration Cost Comments Oracle usage
0 Simple striping, no
redundancy
Same cost as unprotected
storage.
The term RAID-0 is used
to describe striping,
which increases read
and write throughput.
However, this is not
really RAID, as there is
no actual redundancy.
Striping simplifies administration
for Oracle datafiles. Suitable
for all types of data for which
redundancy isn??™t required.
1 Mirroring Twice the cost of
unprotected storage.
Same write performance
as a single disk.
Read performance may
improve through servicing
reads from both
copies.
Lack of striping adds complexity
of managing a larger number of
devices for Oracle. Often used for
redo logs, since the I/O for redo
is typically relatively small
sequential writes.
Pages:
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580