Raid Levels Supported By The System - Huawei OceanStor S5600 Initial Configuration Manual

3 Configuring the Storage System

3.2.1 RAID Levels Supported by the System

The S5600 storage system support five RAID levels: RAID 0, RAID 1, RAID 5, RAID 6 and
RAID 10. You can select a RAID level according to the results of comparison between the five
levels.
In terms of reliability, performance, and cost, the five RAID levels are compared as RAID levels
are compared as follows:
l
l
3-6
NOTE
On the OSM3.0 main interface, only the groups of RAID 0, RAID 5, RAID 6, and RAID 10 can be created
directly. To create a RAID 1 group, set the same number of disks in a mirroring group as the number of
member disks in the interface for creating a RAID 10 group.
Reliability
RAID 0 does not provide the redundancy function. If one hard disk is damaged, all data
–
cannot be accessed. The reliability is the lowest and RAID 0 is not suitable for key
services.
RAID 1 backs up the data in real time by using the mirroring technology. In a RAID 1
–
group, one hard disk is the working disk and all the other hard disks are its mirroring
disks. When the system writes data, the data must be written to the working disk and
mirroring disks at the same time; when the system reads data, the data can be read from
the working disk only. When the working disk is faulty, the mirroring disk will take
over its services. After the faulty disk is replaced with a new hard disk, the data stored
on the working disk can be reconstructed and restored. Compared with other RAID
levels, RAID 1 has the highest reliability.
RAID 5 uses cyclic redundancy check (CRC) and distributes the verification data on
–
each member disk in the RAID group. When a member disk in the RAID group fails,
the data on the other member disks in the RAID group can be used to reconstruct the
data on the faulty member disk.
RAID 6 produces the check data by performing two independent logical operations and
–
distributes the check data separately on each member disk in the RAID group. RAID 6
allows the situation that two member disks are faulty at the same time. The data on the
faulty disk can be reconstructed by the data on other member disks.
RAID 10 stores data on the member disks in the RAID group in a distributed way and
–
provides a mirroring disk for each member disk in mirroring group so that data is stored
in full redundancy mode. RAID 10 is more reliable than RAID 5.
Read and write performance
RAID 0 supports concurrent read and write operations to provide the highest read/write
–
speed.
For RAID 1, when the system writes data, the data must be written to the working disk
–
and mirroring disks at the same time; when the system reads data, the data can be read
from the working disk only. Therefore, RAID 1 has lower read and write performance
than other RAID levels.
NOTE
On the OSM3.0 main interface, only the groups of RAID 0, RAID 5, and RAID 10 can be created
directly. To create a RAID 1 group, set the same number of disks in a mirroring group as the
number of member disks in the interface for creating a RAID 10 group.
RAID 5 is recommended for an application of many write operations. Generally, RAID
–
5 has higher write performance but lower read performance than RAID 10.
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OceanStor S5600 Storage System
Initial Configuration Guide
Issue 02 (2009-09-30)