RAID 5-distributed data guarding | HP Smart Storage Adstrator

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

Advantages:

•This method has the highest read performance of any fault-tolerant configuration.

•No data is lost when two drives fail, as long as no two failed drives are mirrored to another failed drive.

•Up to two-thirds of the physical drives in the array can fail.

Disadvantages:

•This method is expensive, because many drives are needed for fault tolerance.

•Only one-third of the total drive capacity is usable for data storage.

RAID 5—distributed data guarding

In a RAID 5 configuration, data protection is provided by parity data (denoted by Px,y in the figure). This parity data is calculated stripe by stripe from the user data that is written to all other blocks within that stripe. The blocks of parity data are distributed evenly over every physical drive within the logical drive.

When a physical drive fails, data that was on the failed drive can be calculated from the remaining parity data and user data on the other drives in the array. This recovered data is usually written to an online spare in a process called a rebuild.

This configuration is useful when cost, performance, and data availability are equally important.

Advantages:

•Has high read performance.

•Data is not lost if one physical drive fails.

•More drive capacity is usable than with RAID 1+0—parity information requires only the storage space equivalent to one physical drive.

Disadvantages:

•Has relatively low write performance.

Troubleshooting 123

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HP Smart Storage Adstrator manual RAID 5-distributed data guarding

Contents

HP Smart Storage Administrator User Guide Page Contents Optional components 130 About HP SSA Benefits of using HP SSA Support for configuration tasks Procedure HP Smart Array Array configuration guidelines Array configuration Minimum requirements Native support for 64-bit and 32-bit operating systems Launching HP SSA during Post Gen8 or later Accessing HP SSA in the offline environment Launching HP SSA from an ISO image all generations Mounting the image through iLOBurning the image to a CD or DVD Installing the image on a PXE server Set up PXELinuxPrerequisites Specify the ISO image path Configure PXELinux Supported network file systems Accessing HP SSA in the online environment Launching HP SSA on a local server Hpssa- hHttp//servername2301 Operations Icon and key stroke legend Using the HP SSA GUI Navigating the GUI Configure screen When a controller is selected, the following elements appear Diagnostics screen HP SSA help Configuration tasks Configuring a controller Performing a Configuration task HP SSD Smart Path Operations Rapid Parity Initialization SSD Over Provisioning Optimization Operations Changing the Spare Management mode Changing the Spare Activation Mode Operations Cache Manager Operations About HP SmartCache Enable HP SmartCache Operations Operations Installing a license key with HP SmartCache Enabling SmartCache Write-back Operations Splitting a mirrored array Working with mirrored arrays Recombining a split mirrored array Creating a split mirror backup Healing an array Replacing an array Setting Auto RAID Click Create Arrays with RAID Operations Managing FLS Setting Managing modes RAID mode or HBA mode Operations Power modes Viewing controller status Performing a Diagnostics task Diagnostic tasks Operations Root@localhost root# hpssacli Using the HP SSA CLIOpening the CLI in Console mode \Program Files\hp\hpssacli\Bin\hpssacli.exe Target variable Opening the CLI in Command modeCommand variable CLI syntax = ctrl ch=Lab4 ld 1 modify raid=0 ss=? Available options are Current value DefaultQuerying a device Hiding warning prompts Target show detailstatus Show commandTarget controller show config detail Keyword abbreviations = ctrl all show Version Help command= ctrl ch=lab4 show config Displaying the current versions of the application layers Typical procedures Setting the boot controllerSetting the boot volume = set target ctrl slot=3 = clear target Setting the targetIdentifying devices Set target target Target delete forced Generating a diagnostic reportDeleting target devices Target modify led=onoff Optimizing controller performance for video Erasing a physical driveRescanning the system Entering or deleting a license key Target create type=ld parameter=value Creating a logical drive Sample scenario Available options are +0 default value Moving a logical drive Target modify newarray=Target modify drives=# ##,# ##,# ##-# ## SmartCache in Hpssacli Viewing enclosure informationViewing SSD physical drives Viewing SSD information = ctrl slot=1 array B create type=ldcache datald=2 Rapid Parity Initialization methodsSSD Over Provisioning Optimization Assigning a chassis name to the controller Controller slot=1 modify spareactivationmode=predictive Setting the spare activation modeManaging spare drives Target modify spareactivationmode= failure predictive Spare Management Mode in Hpssacli Expanding an arrayShrinking an array Moving an array Target remove drives=###-###Target modify drives=###-### spares=###-### Extending a logical drive = ctrl slot=1 create type=arrayr0 drives=allunassignedTarget modify size=#max? forced Target modify preferredpathmode=automaticmanual? Setting the preferred path modeTarget modify raid=01+0156adg? ss=8163264128256default? Migrating a logical drive Changing the Rebuild Priority setting Disabling a redundant controllerAssigning a redundant controller to a logical drive Re-enabling a failed logical drive Changing the Expand Priority settingSetting the surface scan mode Changing the surface scan delay time Changing the controller cache ratio Enabling or disabling the drive cacheEnabling or disabling the array accelerator Enabling SmartCache Write-back Enabling a script to exit on errorUsing the Split Mirror command Set exitonerror=enable set eoe=disable Show exitonerror Target modify hbamode=onoff? HBA modeTarget modify latency=lowhighdisable? Controller slot=5 modify latency=low Using HP SSA scripting Power modeRAID mode Hpssascripting -c Filename -internal -external -e Filename Capturing a configurationUsing an Input script Creating an HP SSA script file Sample custom input script Script file requirements Date captured Wed Jan 15 153314 Version Sample custom capture script Sample encryption script Initial encryption configuration PlainText= Enable Encryption configuration Script file options Controller category Action modeMethod mode Control category ClearConfigurationWithDataLoss ControllerCacheState DriveWriteCache DPOEnableElevatorSortEnable IRPEnable LicenseKey, DeleteLicenseKey MNPDelayNoBatteryWriteCache Power modes RapidParityInitialization SurfaceScanDelaySurfaceScanDelayExtended QueueDepth ArrayR0 DPOEnable = No ElevatorSortEnable = Yes IRPEnable = NoArray category Array OnlineSpareMode CachingArrayDrive DriveType Logical Drive category OnlineSpareSplitMirror ArrayAccelerator LogicalDriveCachingLogicalDrive CachedLogicalDrive NumberOfParityGroupsPreferredPath Repeat SetBootVolumePrimarySetBootVolumeSecondary Renumber StripSize SizeSizeBlocks SmartCache Write-back Encryption controller category Encryption support commands Remove Suspend Resume ControllerPasswordMode EncryptionRecoveryQuestion Encryption logical volume category XML support XML output\hpssascripting -c out.xml XML input XML input file DTD Comment or clarification Code HP SSA scripting warning messages Error code Error message Comment or clarification HP SSA scripting error messages This error can occur when you attempt to add or Or logical drive Free space for the requested size 3011 Expand array and changed the size or RAID level ACCEPTEULA=YES HP Smart Storage Administrator Diagnostics Utility CLI About the utilityReported information Troubleshooting Field Description Installing the utility Launching the utility in CLI mode Diagnostic report proceduresSmartSSD Wear Gauge report procedures Identifying and viewing SmartSSD Wear Gauge report files Drive arrays and fault-tolerance methods512e Physical drive support Drive arrays Troubleshooting Troubleshooting Effects of a hard drive failure on logical drives Fault-tolerance methods RAID 1 and RAID 1+0 RAID RAID 0-No fault tolerance Troubleshooting RAID 1 ADM and RAID 10 ADM RAID 5-distributed data guarding RAID 6 ADG-Advanced Data Guarding RAID Comparing the hardware-based RAID methods Selecting a RAID method Alternative fault-tolerance methods Diagnosing array problems Diagnostic toolsTroubleshooting resources Troubleshooting HP Secure Encryption Optional components About Saap HP Smart Array Advanced Pack ILO Acronyms and abbreviations PXE Documentation feedback Index HP Smart Storage Administrator Diagnostics Utility XML DTD