Raid 1 - Disk Mirroring / Disk Duplexing; Raid 5 - Data Striping With Striped Parity; Figure 112. Raid 1 - Disk Mirroring / Disk Duplexing; Figure 113. Raid 5 - Data Striping With Striped Parity - Intel SSR212CC User Manual

RAID Levels

RAID 1 - Disk Mirroring / Disk Duplexing

All data is stored twice, once each on two identical hard disks making one drive a
"mirror" image of the other. When one hard disk fails, all data is immediately available on
the other without any impact on performance and data integrity.
With Disk Mirroring, two hard disks are mirrored on one I/O channel. If each hard disk is
connected to a separate I/O channel, it is called Disk Duplexing.
RAID 1 represents an easy and highly efficient solution for data security and system
availability. It is especially suitable for installations that are not too large (the available
capacity is only half of the installed capacity). Disk mirroring requires two drives and
each mirrored set is limited to two drives.
RAID Adapter

Figure 112. RAID 1 - Disk Mirroring / Disk Duplexing

RAID 5 - Data Striping with Striped Parity

RAID 5 works in the same way as RAID 0. The data is striped across the hard disks and
the controller calculates redundancy data (parity information) that is striped across all
hard disks. Should one hard disk fail, all data remains fully available. Missing data is
recalculated from existing data and parity information. The RAID 5 disk array delivers a
balanced throughput. Even with small data blocks, which are very likely in a multi-tasking
and multi-user environment, the response time is very good. RAID 5 is particularly
suitable for systems with medium to large capacity requirements, due to the efficient ratio
of installed and available capacity. RAID 5 requires a minimum of three drives in the
configuration but can expand to the physical drive capacity of the controller.
RAID Adapter

Figure 113. RAID 5 - Data Striping with Striped Parity

120
RAID 1
ABC
Available Capacity
N=# disks
C = Disk Capacity
Available Capacity =
(N*C) /2
RAID 5
ABCDEF
Available Capacity
N=# disks
C = Disk Capacity
Available Capacity =
(N*C)(N-1) /N
Intel® Storage System SSR212CC User Guide
A A
B B
C C
Disk Mirroring
RAID 1
P1
A B
D
C P2
E F
P3
Data Striping &
Striped Parity
RAID 5