NEC BladeServer Express5800 Series User Manual page 88

RAID Levels
This section details the RAID levels which the on-board RAID (LSI Logic MegaRAID SAS PCI
EXPRESS ROMB) can support.
Characteristics of RAID Levels
The table below lists the characteristics of the RAID levels.
Level Function
RAID0 Striping
RAID1 Mirroring
RAID5 Striping of both data
and redundant data
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 (disk 1), 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.
IMPORTANT:
defected, the data saved in the HDD cannot be recovered.
Redundancy
No
Yes
Yes
RAID 0 cannot have data redundancy. If a HDD is
Disk array controller
HDD 1
Stripe 1
Stripe 4
Configuring Your Server 4-31
Characteristics
•
Data read/write at the highest rate
•
Largest capacity
•
Capacity: (capacity of single HDD) ×
(number of HDDs)
•
Two HDDs required
•
Capacity: capacity of single HDD
•
Three or more HDDs required
•
Capacity: (capacity of single HDD) ×
((number of HDDs) - 1)
HDD 2
Stripe 2
Stripe 5
HDD 3
Stripe 3
Stripe 6