Managing Software Raids With Evms; Understanding Software Raids On Linux; What Is A Software Raid - Novell LINUX ENTERPRISE SERVER 10 - STORAGE ADMINISTRATION GUIDE 7-2007 Administration Manual

Table of Contents

Managing Software RAIDs with

EVMS

This section describes how to create and manage software RAIDs with the Enterprise Volume

Management System (EVMS). EVMS supports only RAIDs 0, 1, 4, and 5 at this time. For RAID 6

and 10 solutions, see

Chapter 7, "Managing Software RAIDs 6 and 10 with mdadm," on page

Section 6.1, "Understanding Software RAIDs on Linux," on page 59

Section 6.2, "Creating and Configuring a Software RAID," on page 65

Section 6.3, "Expanding a RAID," on page 69

Section 6.4, "Adding or Removing a Spare Disk," on page 70

Section 6.5, "Managing Disk Failure and RAID Recovery," on page 71

Section 6.6, "Monitoring Status for a RAID," on page 74

Section 6.7, "Deleting a Software RAID and Its Data," on page 79

6.1 Understanding Software RAIDs on Linux

Section 6.1.1, "What Is a Software RAID?," on page 59

Section 6.1.2, "Overview of RAID Levels," on page 60

Section 6.1.3, "Comparison of RAID Performance," on page 61

Section 6.1.4, "Comparison of Disk Fault Tolerance," on page 61

Section 6.1.5, "Configuration Options for RAIDs," on page 62

Section 6.1.6, "Guidelines for Component Devices," on page 62

Section 6.1.7, "RAID 5 Algorithms for Distributing Stripes and Parity," on page 63

Section 6.1.8, "Multi-Disk Plug-In for EVMS," on page 65

Section 6.1.9, "Device Mapper Plug-In for EVMS," on page 65

6.1.1 What Is a Software RAID?

A RAID combines multiple devices into a multi-disk array to provide resiliency in the storage

device and to improve storage capacity and I/O performance. If a disk fails, some RAID levels keep

data available in a degraded mode until the failed disk can be replaced and its content reconstructed.

A software RAID provides the same high availability that you find in a hardware RAID. The key

operational differences are described in the following table:

Comparison of Software RAIDs and Hardware RAIDs

Table 6-1

Feature

RAID function

Linux Software RAID

Multi-disk (md) driver or mdadm

Hardware RAID

RAID controller on the disk array