Enclosure Management; Raid Levels; Summary Of Raid Levels - Lenovo ThinkServer RD650 User Manual

12Gb/s MegaRAID SAS Software User Guide
March 2014
Table 6 Beep Codes, Events, and Virtual Drive States
RAID 0 virtual drive loses a virtual drives
RAID 1 loses a mirror drive
RAID 1 loses both drives
RAID 5 loses one drive
RAID 5 loses two or more drives
RAID 6 loses one drive
RAID 6 loses two drives
RAID 6 loses more than two drives
A hot spare completes the rebuild process and is
brought into a drive group
2.1.19

Enclosure Management

Enclosure management is the intelligent monitoring of the disk subsystem by software, hardware or both. The disk
subsystem can be part of the host computer or can reside in an external disk enclosure. Enclosure management helps
you stay informed of events in the disk subsystem, such as a drive or power supply failure. Enclosure management
increases the fault tolerance of the disk subsystem.
2.2

RAID Levels

The RAID controller supports RAID levels 0, 00, 1, 5, 6, 10, 50, and 60. The supported RAID levels are summarized in the
following section.
In addition, the RAID controller supports independent drives (configured as RAID 0 and RAID 00.) The following
sections describe the RAID levels in detail.
2.2.1

Summary of RAID Levels

RAID 0 uses striping to provide high data throughput, especially for large files in an environment that does not require
fault tolerance.
RAID 1 uses mirroring so that data written to one drive is simultaneously written to another drive. RAID 1 is good for
small databases or other applications that require small capacity but complete data redundancy.
RAID 5 uses disk striping and parity data across all drives (distributed parity) to provide high data throughput,
especially for small random access.
RAID 6 uses distributed parity, with two independent parity blocks per stripe, and disk striping. A RAID 6 virtual drive
can survive the loss of any two drives without losing data. A RAID 6 drive group, which requires a minimum of three
drives, is similar to a RAID 5 drive group. Blocks of data and parity information are written across all drives. The parity
information is used to recover the data if one or two drives fail in the drive group.
A RAID 00 drive group is a spanned drive group that creates a striped set from a series of RAID 0 drive groups.
RAID 10, a combination of RAID 0 and RAID 1, consists of striped data across mirrored spans. A RAID 10 drive group is
a spanned drive group that creates a striped set from a series of mirrored drives. RAID 10 allows a maximum of 8 spans.
You must use an even number of drives in each RAID virtual drive in the span. The RAID 1 virtual drives must have the
same stripe size. RAID 10 provides high data throughput and complete data redundancy but uses a larger number of
spans.
Event Virtual Drive State
Offline
Degraded
Offline
Degraded
Offline
Partially Degraded
Degraded
Offline
N/A
LSI Corporation
- 27 -
Chapter 2: Introduction to RAID
Beep Code
3 seconds on and 1 second off
1 second on and 1 second off
3 seconds on and 1 second off
1 second on and 1 second off
3 seconds on and 1 second off
1 second on and 1 second off
1 second on and 1 second off
3 seconds on and 1 second off
1 second on and 3 seconds off
RAID Levels