NEC Express 5800, User Manual

Page: 325 / 719

Hardware
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RAID0
In RAID0, 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.
RAID1
In the RAID1 level, data saved in a HDD is written to another HDD without change. The mode is
called "mirroring".
When data is written onto a single HDD, the same data is written onto another HDD. If either of
the HDDs is defected, the other HDD containing the same data can substitute for the defected
HDD. Thus the system can continue to operate without interruption.
IMPORTANT:
RAID0 cannot have data redundancy. If a HDD is defected, the data
saved in the HDD cannot be recovered.
HDD 1
RAID Controller
HDD 2 HDD 3
Stripe 1
Strip1
Stripe 4
Stripe 2
Stripe 5
Stripe 3
Stripe 6
HDD 1
RAID Controller
HDD 2
Stripe 1
Stripe 2
Stripe 1
Stripe 2