Specifications

10 en | RAID Functions: Introduction SCSI to SATA RAID Subsystem | Administrator’s Manual
F.01U.027.802 | V1 | 2006.11 Bosch Security Systems
1.3 RAID Levels
Using a RAID storage subsystem has the following advantages:
• Provides disk spanning by weaving all connected drives into one single volume.
• Increases disk access speed by breaking data into several blocks when reading/writing to
several drives in parallel. With RAID, storage speed increases as more drives are added as
the channel bus allows.
• Provides fault-tolerance by mirroring or distributing parity across disk drives.
RAID Level Description Capacity Data Availability
NRAID Non-RAID N None
RAID0 Disk Striping N Less than one single drive
RAID1 (0+1) Mirroring Plus Striping (if
N>1)
N/2 high
==RAID5
RAID3 Striping with Parity on dedi-
cated disk
N-1 high
==RAID5
RAID5 Striping with interspersed
parity
N-1 high
==RAID5
RAID 10
(Logical Volume)
Striping with RAID1 logical
drives
/high
>>RAID5
RAID 30
(Logical Volume)
Striping with RAID3 logical
drives
/high
>>RAID5
RAID 50
(Logical Volume)
Striping with RAID5 logical
drives
/high
>>RAID5
Table 1.1 A Brief on RAID Levels
i
NOTICE!
Drives on different channels can be included in a logical drive, and logical drives of different
RAID levels can be used to compose a logical volume. There are more combinations than RAID
10, 30, and 50.
RAID Level Performance Sequential Performance Random
NRAID Drive Drive
RAID0 R: Highest
W: Highest
R: High
W: Highest
RAID1 (0+1) R: High
W: Medium
R: Medium
W: Low
RAID3 R: High
W: Medium
R: Medium
W: Low
RAID5 R: High
W: Medium
R: High
W: Low