NEC N8103-89 Manuale Utente
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2. RAID Levels
This section details the RAID levels which the disk array controller can support.
2-1. Characteristics of RAID Levels
The table below lists the characteristics of the RAID levels.
Level Function
Redundancy
Characteristics
RAID0
Striping
No
Data read/write at the highest rate
Largest capacity
Capacity: (capacity of single HDD) ×
Largest capacity
Capacity: (capacity of single HDD) ×
(number of HDDs)
RAID1
Mirroring
Yes
Two HDDs required
Capacity: capacity of single HDD
Capacity: capacity of single HDD
RAID5
Striping of both data
and redundant data
and redundant data
Yes
Three or more HDDs required
Capacity: (capacity of single HDD) ×
Capacity: (capacity of single HDD) ×
((number of HDDs) - 1)
RAID10
Combination of striping
and mirroring
and mirroring
Yes
Four HDDs required
Capacity: (capacity of single HDD) × 2
Capacity: (capacity of single HDD) × 2
2-2. RAID0
In RAID 0, data to be recorded is distributed to HDDs. The mode is called "striping."
In the figure below, data is recorded in stripe 1 (disk1), stripe 2 (disk 2), and stripe 3 (disk
3)… in the order. Because RAID0 allows all HDDs to be accessed collectively, it can
provide the best disk access performance.
3)… in the order. Because RAID0 allows all HDDs to be accessed collectively, it can
provide the best disk access performance.
Notice
RAID 0 cannot have data redundancy. If a HDD is defected, the data saved
in the HDD cannot be recovered.
in the HDD cannot be recovered.
Disk array controller
Disk 1
Disk 2
Stripe 1
Disk 3
Stripe 4
Stripe 2
Stripe 5
Stripe 3
Stripe 6