HP LH4r Integrated HP NetRaid Controller Configuration Guide - Page 16

Arrays with No Redundancy: RAID Level 0

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Chapter 2 RAID Overview Arrays with No Redundancy: RAID Level 0 RAID 0: Striping In RAID 0 configurations, data is distributed among hard disks in the array via an algorithm called striping. Data written to a logical drive is divided into pieces called blocks. RAID 0 provides no data redundancy. If one hard disk fails, the data is lost from the entire logical drive and must be retrieved from a backup copy. If you have five physical drives configured as one RAID 0 logical drive, data blocks are written as follows: Disk 1 Disk 2 Disk 3 Disk 4 Disk 5 Stripe 1 Stripe 2 Block 1 Block 6 Block 2 Block 7 Block 3 Block 8 Block 4 Block 9 Block 5 Block 10 The RAID 0 algorithm allows data to be accessed on multiple disks simultaneously. Read and write performance on a multidisk RAID 0 system is significantly faster than on a single drive system. RAID 0 Advantages Provides maximum data capacity, because all disk space is used for data. Costs are low, because no disk space is allocated for redundancy. Access time is fast for both reads and writes. RAID 0 Disadvantages RAID 0 provides no redundancy so if a hard drive fails, data must be restored from backup. Hot spares cannot be used with RAID 0 configurations. RAID 0 Summary Choose RAID 0 if redundancy is not required, and you need fast performance and low costs. 10

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Chapter 2
RAID Overview
10
Arrays with No Redundancy: RAID Level 0
RAID 0: Striping
In RAID 0 configurations, data is distributed among hard disks in the array via
an algorithm called
striping
. Data written to a logical drive is divided into pieces
called
blocks
.
RAID 0 provides no data redundancy
. If one hard disk fails, the
data is lost from the entire logical drive and must be retrieved from a backup
copy. If you have five physical drives configured as one RAID 0 logical drive,
data blocks are written as follows:
Disk 1
Disk 2
Disk 3
Disk 4
Disk 5
Stripe 1
Block 1
Block 2
Block 3
Block 4
Block 5
Stripe 2
Block 6
Block 7
Block 8
Block 9
Block 10
The RAID 0 algorithm allows data to be accessed on multiple disks
simultaneously. Read and write performance on a multidisk RAID 0 system is
significantly faster than on a single drive system.
RAID 0 Advantages
Provides maximum data capacity, because all disk space is used for data.
Costs are low, because no disk space is allocated for redundancy.
Access time is fast for both reads and writes.
RAID 0 Disadvantages
RAID 0 provides no redundancy so if a hard drive fails, data must be restored
from backup.
Hot spares cannot be used with RAID 0 configurations.
RAID 0 Summary
Choose RAID 0 if redundancy is not required, and you need fast performance and
low costs.