NEC N8103-91, Руководство пользователя

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2-3. 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.
Disk array controller
Disk 1 Disk 2
Stripe 1
Stripe 2
Stripe 1
Stripe 2
2-4. RAID5
In RAID5, data is distributed to HDDs by striping and, at the same time, the parity
(redundant data) is distributed to the HDDs. This mode is called "striping with distributed
parity".
Each of stripe x, stripe x+1, and parity (x, x+1) created from stripe x and stripe x+1 is
written onto a specific HDD. Accordingly, the total capacity assigned to the parity is just the
same as the capacity of a single HDD. If any one of the HDDs configuring a logical drive is
defected, data is still available with no problems.
Disk array controller
Disk 1 Disk 2 Disk 3
Stripe 2
Parity (3, 4)
Stripe 5
Parity (1, 2)
Stripe 3
Stripe 6
Stripe 1
Stripe 4
Parity (5, 6)