Promise Technology TX8, TX4 user manual Choosing a RAID Level, Advantages Disadvantages

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UltraTrak100 TX4 and UltraTrak100 TX8 User Manual

For the Gigabyte Boundary feature to work, the Gigabyte Boundary feature must be set to ON when the original array is created. When enabled, the Gigabyte Boundary feature rounds the drive capacity of all drives to the common whole GB drive size. For example, with the Gigabyte Boundary feature enabled, the remaining working drives can be 20.5 GB and the replacement drive can be 20.3, since all are rounded down to 20GB. This permits the smaller drive to be used. Please note that users will lose a small amount of available storage capacity from each drives in order to arrive at a common drive size.

CHOOSING STRIPE BLOCK SIZE

There are two issues to consider when selecting the Stripe Block Size.

First, you should choose a Stripe Block Size equal-to or smaller than the smallest cache buffer found on any array disk drive. Selecting a larger value slows the array down because disk drives with smaller cache buffers need more time for multiple accesses to fill their buffers.

Secondly, if your data retrieval consists of fixed data blocks, such as with some database or video applications – then you should choose that size as your Stripe Block Size.

CHOOSING A RAID LEVEL

There are several issues to consider when choosing the RAID Level for your UltraTrak100 array. Appendix A - Technology Background on page 41 gives some technical insight regarding each RAID choice and the following discussion summarizes some advantages, disadvantages and applications for each choice.

RAID 0

Advantages

Disadvantages

Implements a striped disk array, the data is

Not a "True" RAID because it is not fault-

broken down into blocks and each block is

tolerant

written to a separate disk drive

The failure of just one drive will result in all

 

I/O performance is greatly improved by

data in an array being lost

spreading the I/O load across many

Should not be used in mission critical

channels and drives

environments

No parity calculation overhead is involved

 

 

 

Recommended Applications for RAID 0

•Image Editing

•Pre-Press Applications

•Any application requiring high bandwidth

RAID 1

Advantages

Disadvantages

Simplest RAID storage subsystem design

High disk overhead - uses only 50% of

Can increase read performance by

total capacity

 

processing data requests in parallel since

 

the same data resides on two different

 

drives

 

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Contents ULTRATRAK100 TX4 ULTRATRAK100 TX8 Trademarks CopyrightImportant Data Protection Information Radio Frequency Interference Statement Table of Contents RAID Page Introduction Architectural DescriptionFeatures and Benefits Feature BenefitInstall Hard Drives ConfigurationGetting Started 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 JbodMaintenance Drive Status IndicatorsIndicator Color Meaning Critical & Offline ArraysWhen a Disk Drive Fails REBUILDING/SYNCHRONIZING Fault Tolerant ArraysReplacing a Disk Drive Module 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 CommentsError Mode Configuration ModeLCD Messages Array FunctionalConfigure Scsi View Status Configure Array Configure CacheView Status View Controller Info View Cache StatsView Array Information View EnclosureView Controller Information Temperature 30C/86F Array 0 Size 12GBRAID 0 Functional 5009 RPMCreate/Cancel Auto Array Setup Press SEL to Create Press Exit to Cancel What you can doView Drive Assignments Define Array 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 Cache Write Cache What you can doWrite Back Write Thru What you can do Write BackMode ID SelectedScsi ID Press Or to move these items on the LCD What you can doTechnical Support Services Contacting Promise SupportUSA Tech Support Center 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?
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