Sun Microsystems 440 manual Hardware Disk Mirroring, RAID 5 Disk Striping With Parity, Hot-Spares

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On the Netra 440 server, you can configure hardware disk mirroring using the on- board Ultra-4 SCSI controller. This provides higher performance than with conventional software mirroring using volume management software. For more information, see:

■“To Create a Hardware Disk Mirror” on page 57

■“To Delete a Hardware Disk Mirror” on page 59

■“To Perform a Mirrored Disk Hot-Plug Operation” on page 61

RAID 1 offers the highest level of data protection, but storage costs are high, and write performance compared to RAID 0 or RAID 5 is reduced since all data must be stored twice.

RAID 5: Disk Striping With Parity

RAID 5 is an implementation of disk striping in which parity information is included with each disk write. The advantage of this technique is that if any one disk in a RAID 5 array fails, all the information about the failed drive can be reconstructed from the data and parity on the remaining disks.

System performance using RAID 5 will fall between that of RAID 0 and RAID 1; however, RAID 5 provides limited data redundancy. If more than one disk fails, all data is lost.

Hot-Spares

In a hot-sparesarrangement, one or more hard drives are installed in the system but are unused during normal operation. This configuration is also referred to as hot relocation. Should one of the active drives fail, the data on the failed disk is automatically reconstructed and generated on a hot-spare disk, enabling the entire data set to maintain its availability.

Hardware Disk Mirroring

On the Netra 440 server, the Ultra-4 SCSI controller supports internal hardware disk mirroring using the Solaris OS raidctl utility.

A hardware disk mirror created under the raidctl utility behaves slightly differently than one created using volume management software. Under a software mirror, each device has its own entry in the virtual device tree, and read/write operations are performed to both virtual devices. Under hardware disk mirroring,

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Contents Netra 440 Server System Administration Guide Page Contents Managing RAS Features and System Firmware Managing Disk Volumes Iv Netra 440 Server System Administration Guide August Figures Vi Netra 440 Server System Administration Guide August Tables Viii Netra 440 Server System Administration Guide August Preface How This Book Is OrganizedUsing Unix Commands Shell PromptsTypographic Conventions Related DocumentationContacting Sun Technical Support Accessing Sun DocumentationThird-Party Web Sites Sun Welcomes Your CommentsConfiguring the System Console Communicating With the System1Ways of Communicating With the System Using the System Console What the System Console DoesSerial MGT NET MGT Alom serial management port Alom network management port Alternative System Console Configuration 3Alternative Console Ports Require Additional ConfigurationAccessing the System Console Through a Graphics Monitor About the sc Prompt Access Through Multiple Controller Sessions OpenBoot ok PromptReaching the sc Prompt Reaching the ok Prompt Graceful Shutdown Alom System Controller break or console CommandL1-A Stop-A Keys or Break Key Externally Initiated Reset XIR Manual System ResetFor More Information Getting to the ok Prompt2Ways of Accessing the ok Prompt To Get to the ok PromptConsole # Accessing the System Controller Using the Serial Management PortTo Use the Serial Management Port Activating the Network Management PortEstablish an Alom system controller session To Activate the Network Management Port To verify the network settings, typeLog out of the Alom system controller session Accessing the System Console Through a Terminal Server To Access The System Console Through a Terminal Server3Pin Crossovers for Connecting to a Typical Terminal Server Open a terminal session on the connecting device, and type Accessing the System Console Through a TIP Connection Power on the systemTo Access the System Console Through the TIP Connection A shell tool window on the Sun system, typeOk power-off Modifying the /etc/remote File If the number displayed by the uname -rcommand is less thanTo Modify the /etc/remote File Netra 440 Server System Administration Guide August Ok setenv input-device ttyb ok setenv output-device ttyb Open a shell tool window Type Verifying Serial Port Settings on TtybTo Verify the Serial Port Settings on Ttyb Look for the following outputFor more information, see Getting to the ok Prompt on To cause the changes to take effect, type System Console OpenBoot Configuration Variable Settings Output-device Ttya Ttyb Screen Input-device KeyboardNetra 440 Server System Administration Guide August Managing RAS Features and System Firmware Alom System Controller Logging In To the Alom System ControllerAbout the scadm Utility To Log In To the Alom System ControllerTo View Environmental Information Sc showenvironmentControlling the Locator LED To turn on the Locator LED, do one of the followingTo turn off the Locator LED, do one of the following OpenBoot Emergency Procedures Stop-A Functionality To Restore OpenBoot Configuration DefaultsStop-N Functionality Stop-F Functionality Automatic System RecoveryTo reset the system, type the following command Stop-D FunctionalityAuto-Boot Options Error Handling Summary Enabling and Disabling Automatic System Recovery Reset ScenariosAutomatic System Recovery User Commands To Enable Automatic System RecoveryTo cause the parameter changes to take effect, type To Disable Automatic System RecoveryTo cause the parameter change to take effect, type Obtaining Automatic System Recovery Information Unconfiguring and Reconfiguring DevicesTo Unconfigure a Device Manually To determine full physical device paths, type To Reconfigure a Device Manually To Enable the Hardware Watchdog Mechanism Enabling the Hardware Watchdog Mechanism and Its OptionsMultipathing Software Managing Disk Volumes Disk VolumesVeritas Dynamic Multipathing Volume Management SoftwareSun StorEdge Traffic Manager Managing Disk Volumes RAID Technology Disk ConcatenationRAID 0 Disk Striping RAID 1 Disk MirroringRAID 5 Disk Striping With Parity Hardware Disk MirroringHot-Spares To Create a Hardware Disk Mirror C1t3d0 Devices/pci@1f,700000/scsi@2/sd@3,0For example To Delete a Hardware Disk Mirror To delete the volume, type the following command To confirm a failed disk, type the following command To Perform a Mirrored Disk Hot-Plug OperationTo Perform a Non-Mirrored Disk Hot-SwapOperation View the status of the Scsi devices CD-ROMRemove the hard drive from the device tree # cfgadm -x removedevice c0dsk/c1t1d0Configure the new hard drive Verify that the device has been removed from the device treeVerify that the new hard drive is in the device tree OpenBoot Configuration Variables Baudrate, bits Appendix a OpenBoot Configuration Variables Netra 440 Server System Administration Guide August Alarm Relay Output Application Programming Interface Netra 440 Server System Administration Guide August Page Netra 440 Server System Administration Guide August Page Netra 440 Server System Administration Guide August Symbols IndexNetra 440 Server System Administration Guide August Asr-disable, 46 go Console, 11, 41 console -f, 9 poweroff, 12 poweron Uadmin 11 uname, 25 uname -r Netra 440 Server System Administration Guide August