HP Microsoft Windows Server 2003 for Itanium-based Systems specification

RAID 1+0—drive mirroring

In a RAID 1+0 configuration, data is duplicated to a second drive.

When the array has more than two physical drives, drives are mirrored in pairs.

In each mirrored pair, the physical drive that is not busy answering other requests answers any read requests that are sent to the array. (This behavior is called load balancing.) If a physical drive fails, the remaining drive in the mirrored pair can still provide all the necessary data. Several drives in the array can fail without incurring data loss, as long as no two failed drives belong to the same mirrored pair.

This fault-tolerance method is useful when high performance and data protection are more important than the cost of physical drives.

NOTE: When there are only two physical drives in the array, this fault-tolerance method is often referred to as RAID 1.

Advantages:

•Has the highest read performance of any fault-tolerant configuration.

Drive arrays and fault-tolerance methods 62

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HP Microsoft Windows Server 2003 for Itanium-based Systems manual RAID 1+0-drive mirroring

Contents

HP Array Configuration Utility User Guide Audience assumptions Contents Diagnosing array problems Getting started Features and system requirementsInstalling ACU This section Comparison of ACU execution modes Overview for using ACUSetting the execution mode for Microsoft Windows Opening ACU in Local Application mode Choosing an operating mode Opening ACU in Browser mode Http//servername2301 Opening ACU through Systems Insight Manager Select Device Queries Typical Standard mode screen GUI operating modes Typical Configuration Wizards mode screen Completing the configuration process Typical Express Configuration mode screen Possible tasks in Standard Configuration mode Configuring a new controllerUsing Standard Configuration mode Using Express Configuration mode Click Finish Using the configuration wizardsCreating an array Click Create an array, and then click Begin Configuring a new controller Creating a logical drive Click Create a logical drive, and then click Begin Configuring a new controller Choices available after opening ACU Modifying an existing configurationModifying a configuration using Standard Configuration mode Clear Configuration Modifying a configuration using Express modeModifying a configuration using the Configuration wizards Click Express Configuration, and then click Begin Create an array Controller settingsClick Controller Settings, and then click Begin Create a logical drive Delete arrays Click Delete logical drives, and then click Begin Delete logical drivesExpand Array Click Extend logical drive, and then click Begin Extend logical driveMigrate a logical drive Click Migrate a logical drive, and then click Begin RA4x00 controllers Spare managementSelective Storage Presentation Click Spare Management, and then click Begin MSA and Smart Array Cluster storage controllers Configuring switches Click ACU Switch Configuration Splitting a mirrored array Recombining a split, mirrored array Modifying an existing configuration Introduction to scripting in ACU Command line syntaxScripting in ACU Operating modes Sample custom input script Cpqacuxe -i Filename Script file options Description of option categories in ACU scripting Action Control categoryController category Method LicenseKey, DeleteLicenseKey ClearConfigurationWithDataLossController RAIDArrayID RebuildPriority, ExpandPriority SurfaceScanDelayArray category SSPState Drive Logical Drive categoryOnlineSpare LogicalDrive StripeSize SizeSectors ArrayAccelerator ConnectionName Error reportingSSPAdaptersWithAccess HostMode ACU scripting error messages 0-9, !, @, #, *, , , ,, -, , +, , ., /, and space. The ID Current configuration Running the CLI Using the Command Line InterfaceOverview of the ACU CLI Keyword abbreviations Command variableCLI syntax Target variable Hiding warning prompts Typical proceduresExample command Querying a device Sample scenario Syntax Example Example commandsModifying the controller chassis name Using Selective Storage Presentation Sample scenario Modifying connection names Managing host modes connection profiles Expanding an array Deleting target devicesIdentifying devices Extending a logical drive Migrating a logical drive Target modify raid=01+0156adg? ss=8163264128256default?Managing spare drives Target modify size=#max? forced Changing the controller cache ratio Changing the Rebuild Priority settingChanging the Expand Priority setting Enabling or disabling the drive cache Changing the surface scan delay timeRe-enabling a failed logical drive Disabling a redundant controller Setting the targetEnabling or disabling the array accelerator Typical scenario Rescanning the system = rescan Probability of logical drive failure Factors involved in logical drive failure Probability of logical drive failure Drive arrays and fault-tolerance methods Drive arrays Drive arrays and fault-tolerance methods Fault-tolerance methods Hardware-based fault-tolerance methods Disadvantages RAID 0-No fault toleranceAdvantages RAID 1+0-drive mirroring RAID 5-distributed data guarding RAID 6 ADG-Advanced Data Guarding Comparing the hardware-based RAID methods RAID RAID 6 ADG Alternative fault-tolerance methods Selecting a RAID method Server Diagnostics Diagnosing array problemsDiagnostic tools Post messages Acronyms and abbreviations SSP Index Index