Technical white paper | AHCI and RAID on HP rp7800, rp5810, and rp5800 Retail Systems
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RAID 0 with two hard drives (striped)
HP supports RAID 0, but we do not recommend it for business PC users. Lack of redundancy causes less than half the
reliability of a single hard drive system since the Mean Time Between Failure (MTBF) of RAID 0 is equal to the MTBF of an
individual drive, divided by the number of drives.
Table 2. RAID 0 with two hard drives (striped).
First disk
Second disk
Data Segment 1 Data Segment 2
Data Segment 3 Data Segment 4
Data Segment 5 Data Segment 6
Data Segment 7 Data Segment 8
Data Segment 9 Data Segment 10
Data Segment 11 Data Segment 12
Data Segment 13 Data Segment 14
Data Segment 15 Data Segment 16
In table 2, each “Data Segment n” represents a group of data, known as a strip. In this case, each row represents a stripe.
RAID 0 represented in the table above shows how information is segmented, made into chunks or strips, and stored across
the stripes of the hard drive members of this RAID volume.
To illustrate the concept of RAID 0 and striping, Figure 1 shows how a sequence of data “ABCD...” is stored in a RAID 0 mode.
In this example, each letter represents a segment or strip. The graphic shows how the various pieces of the information go
to different hard drives. If any segment of RAID 0 fails, all information from all members is lost.
At a higher reliability cost with faster performance, HP rp5810 and rp5800 Retail Systems also allow for RAID 0 with three
hard drives. RAID 0 with two or three hard drives is a supported configuration. RAID 0 with three hard drives is shown in
Figure 2.
Figure 2. Performance – RAID 0 with three HDDs.
RAID 1 with two hard drives (Mirroring)
Because it is a very cost-effective way to increase system storage reliability and a great value proposition, RAID 1 is the only
RAID configuration that HP pre-configures for HP rp7800, rp5810, and rp5800 Retail Systems. RAID 1 provides high
availability with minimal performance impact, as well as greater reliability compared to a single hard drive configuration.
A B C D …
A
D
G
J
…
B
E
H
K
…
HDD 1 HDD 2 HDD 3
C
F
I
L
…
A B C D …
A
C
E
G
…
B
D
F
H
…
HDD 1 HDD 2
Figure 1. Performance – RAID 0 with two HDDs
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