If youlose any of the disks, youcan solve the equation to identify the missing
component. For example, if youlose the B drive youcan solve the formula
as:
B = E ??“ A ??“ C ??“ D
There are a number of different disk configurations or types of RAID technology,
which are formally termed levels. The basics of RAID technology were introduced in
Chapter 7, but Table 11-2 summarizes the most relevant levels of RAID in a bit more
detail, in terms of their cost, high availability, and the way Oracle uses each RAID
level.
Which RAID Levels Should You Use with Oracle?
Some people say that you should never use RAID-5 for an Oracle database because of
the degraded write performance of this level of RAID. RAID-1 and RAID-0+1 offer better
performance, but at double the cost of disk storage. RAID-5 offers a cheaper and
reasonable solution, provided that you can meet performance requirements despite the
extra write overhead for maintaining parity data. Use these generic guidelines to help
determine the appropriate uses of different RAID levels:
??? Use RAID-1 for redo log files.
Pages:
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579