Promise Technology TX8, TX4 user manual RAID 3 Block Striping with Parity Drive

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UltraTrak100 TX4 and UltraTrak100 TX8 User Manual

RAID 3 – BLOCK STRIPING WITH PARITY DRIVE

RAID level 3 organizes data across the physical drives of the array, and stores parity information on to a drive dedicated to this purpose. This organization allows increased performance by accessing multiple drives simultaneously for each operation, as well as fault tolerance by providing parity data. In the event of a hard drive failure, data can be re-calculated by the RAID system based on the remaining drive data and the parity information.

The adjustable block size of the RAID 3 array allows for performance tuning based on the typical I/O request sizes for your system. The block size must be set at the time it is created and cannot be adjusted dynamically. Generally, RAID Level 3 tends to exhibit lower random write performance due to the heavy workload going to the dedicated parity drive for parity recalculation for each I/O.

The capacity of a RAID 3 array is the smallest drive size multiplied by the number of drives less one. Hence, a RAID 3 array with (4) 1.0 GB hard drives will have a capacity of 3.0GB. An array with (2) 1.2GB hard drives and (1) 1.0GB hard drive will have a capacity of 2.0GB.

Figure A4. RAID 3 multiple drives stripe data w/ one dedicated parity drive

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Contents ULTRATRAK100 TX4 ULTRATRAK100 TX8 Important Data Protection Information CopyrightTrademarks Radio Frequency Interference Statement Table of Contents RAID Page Introduction Architectural DescriptionFeatures and Benefits Feature BenefitGetting Started Install Hard DrivesConfiguration Unpack ULTRATRAK100UltraTrak100 Disk Drive Access TX4 Shown Connecting the Scsi Cables Back of UltraTrak100 TX4 see for TX8Daisy Chaining Several UltraTrak100s Together Connect Power Cable and Switch Power on Assign a Scsi IDConfigure the ULTRATRAK100 Press SEL to Save Changes Choosing a RAID Level Advantages DisadvantagesCharacteristics/Advantages Disadvantages RAID 0+1Partition and Format the Array JbodIndicator Color Meaning MaintenanceDrive Status Indicators Critical & Offline ArraysReplacing a Disk Drive Module REBUILDING/SYNCHRONIZING Fault Tolerant ArraysWhen a Disk Drive Fails Drive Replacement Drive CarrierConnecting Cables to Disk Drive Replacing a Power Supply Module TX8 onlyBack of UltraTrak100 TX8 ULTRATRAK100 Front Panel Interface Type of Interface Name CommentsLCD Messages Error ModeConfiguration Mode Array FunctionalView Status View Status Configure Array Configure CacheConfigure Scsi View Array Information View Controller InfoView Cache Stats View EnclosureView Controller Information RAID 0 Functional Temperature 30C/86FArray 0 Size 12GB 5009 RPMCreate/Cancel View Drive Assignments Define Array Auto Array SetupPress SEL to Create Press Exit to Cancel What you can do Delete ArrayNo Free Disk What you can do Maxtor Asng In Ary IBM Asng In AryRAID Level 4KB 8KB Maxtor Free IBM Assigned Maxtor FreeWipe out disk Synchronize Array Disable Buzzer Array ID Rebuild/Sync Pri. LowWrite Back Write Thru What you can do Write CacheWrite Cache What you can do Write BackMode ID SelectedScsi ID Press Or to move these items on the LCD What you can doUSA Tech Support Center Technical Support ServicesContacting Promise Support European Tech SupportPacific Rim Sales Office China OfficeLimited Warranty Disclaimer of Other WarrantiesPage Returning Product for Repair USA & Canada Your Responsibilities Appendix a Technology Background Introduction to RAIDRAID 1 Mirroring RAID 0+1 STRIPING/MIRROR RAID 3 Block Striping with Parity Drive RAID 5 Block and Parity Striping Jbod Spanning Appendix B Frequently Asked Questions Why can’t I see the drives on the UltraTrak100 under FDISK?