iv
Table of Contents
Chapter 1 RAID Functions: An Introduction
1.1 Logical Drive................................................................................................... 1
1.2 Logical Volume............................................................................................... 1
What is a logical volume?.................................................................................. 1
1.3 RAID Levels..................................................................................................... 2
What are the RAID levels? ................................................................................ 2
NRAID................................................................................................................ 3
JBOD ................................................................................................................. 3
RAID 0 ............................................................................................................... 4
RAID 1 ............................................................................................................... 4
RAID (0+1)......................................................................................................... 4
RAID 3 ............................................................................................................... 5
RAID 5 ............................................................................................................... 5
1.4 Spare Drives ................................................................................................... 6
Global and Local Spare Drives..........................................................................6
1.5 Identifying Drives ........................................................................................... 8
Flash Selected SCSI Drive ................................................................................ 8
Flash All SCSI Drives ........................................................................................ 8
Flash All but Selected Drives............................................................................. 8
1.6 Rebuild ............................................................................................................9
Automatic Rebuild and Manual Rebuild............................................................. 9
1. Automatic Rebuild ........................................................................................ 9
2. Manual Rebuild........................................................................................... 10
3. Concurrent Rebuild in RAID (0+1).............................................................. 11
1.7 Logical Volume (Multi-Level RAID)............................................................. 12
What is a logical volume?................................................................................ 12
Spare drives assigned to a logical volume? ....................................................14
Limitations:....................................................................................................... 15
Partitioning - partitioning the logical drive or partitioning the logical volume? . 15
Different write policies within a logical volume?............................................... 16
RAID expansion with logical volume?.............................................................. 16
Different controller settings using logical volume? ..........................................16
A logical volume with logical drives of different levels? ................................... 17
Multi-level RAID systems................................................................................. 17
Chapter 2 RAID Planning
2.1 Considerations ............................................................................................... 1
2.2 Configuring the Array:...................................................................................5
2.2.1 Starting a RAID System........................................................................... 5
2.3 Operation Theory ...........................................................................................7
2.3.1 I/O Channel, SCSI ID, and LUN .............................................................. 7
2.3.2 Grouping Drives into an Array .................................................................7
2.3.3 Making Arrays Available to Hosts............................................................9
2.4 Tunable Parameters.....................................................................................10
Chapter 3 Accessing the Array through Serial Port and Ethernet
3.1 RS-232C Serial Port....................................................................................... 1
