Basic Functions; Raid Functions; Supported Raid - Fujitsu ETERNUS DX S5 Series Design Manual

2.

Basic Functions

This chapter describes the functions that control the storage system.

RAID Functions

This section explains the points to note before configuring a system using the ETERNUS DX.

Supported RAID

The ETERNUS DX supports the following RAID levels.
RAID0 (striping)
•
• RAID1 (mirroring)
• RAID1+0 (striping of pairs of mirrored drives)
• RAID5 (striping with distributed parity)
• RAID5+0 (double striping with distributed parity)
• RAID6 (striping with double distributed parity)
RAID6-FR (striping with double distributed parity which provides high-speed rebuild capabilities)
•
IMPORTANT
Remember that a RAID0 configuration is not redundant. This means that if a RAID0 drive fails, the data
will not be recoverable.
This section explains the concepts and purposes (RAID level selection criteria) of the supported RAID levels.
Caution
When Nearline SAS disks that have 6TB or more are used, the available RAID levels are RAID0, RAID1,
RAID6, and RAID6-FR.
■
RAID Level Concept
A description of each RAID level is shown below.
●
RAID0 (Striping)
Data is divided into blocks and allocated across multiple drives.
●
RAID1 (Mirroring)
The data is stored on two duplicated drives at the same time.
If one drive fails, the other drive continues operation.
●
RAID1+0 (Striping of Pairs of Mirrored Drives)
RAID1+0 combines the high I/O performance of RAID0 (striping) with the reliability of RAID1 (mirroring).
●
RAID5 (Striping with Distributed Parity)
Data is divided into blocks and allocated across multiple drives together with parity information created
from the data in order to ensure the redundancy of the data.
●
RAID5+0 (Double Striping with Distributed Parity)
Multiple RAID5 volumes are RAID0 striped. For large capacity configurations, RAID5+0 provides better
performance, better reliability, and shorter rebuilding times than RAID5.
33 Design Guide