Storage Management Overview
49
NAS 2000s Administration Guide
Disadvantages
■
All data on logical drive is lost if a hard drive fails
■
Cannot use an online spare
■
Data can only be preserved by being backed up to external media
RAID 1+0—Drive Mirroring and Striping
In this configuration, information on one drive is duplicated onto a second drive, creating
identical copies of the information as shown in
. Therefore, this method provides the
best fault tolerance. RAID 1+0 requires an even number of drives and is the only method for
fault tolerance protection if only two drives are installed or selected for an array. If more than
two drives are in an array, the data is striped across all of the drives in the array.
Figure 24: RAID 1+0 (drive mirroring) of P1 onto P2
This method is useful when high performance and data protection are more important than the
cost of hard drives. The operating system drives are mirrored. If one drive fails, the mirror
drive immediately takes over and normal system operations are not interrupted.
Note:
HP supports a configuration that uses RAID 1+0 on the system drives in a two drive RAID
array.
Caution:
If two drives being mirrored to each other both fail, data loss occurs.
Advantages
Drive mirroring offers:
■
The highest read and write performance of any fault-tolerant configuration.
■
Protection against data loss if one drive fails.
■
Data preservation in a RAID 1+0 system, when more than one drive fails, as long as none
of the failed drives are mirrored to another failed drive.
P1
P2
B1
B2
B3
B4
B1
B2
B3
B4
Summary of Contents for 345646-001 - StorageWorks NAS 2000s External Storage Server
Page 16: ...About this Guide 16 NAS 2000s Administration Guide ...
Page 56: ...Storage Management Overview 56 NAS 2000s Administration Guide ...
Page 80: ...Disk Management 80 NAS 2000s Administration Guide ...
Page 110: ...User and Group Management 110 NAS 2000s Administration Guide ...
Page 146: ...Folder Printer and Share Management 146 NAS 2000s Administration Guide ...
Page 186: ...NetWare File System Management 186 NAS 2000s Administration Guide ...