Dell H800, H700 manual Example of RAID 60 6 + Advantages of RAID

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RAID 0

RAID 6

RAID 6

Parity	Data 1	Data 2	P parity	Q parity	Data 3	Data 4	P parity	Q parity	Parity
Parity			Q parity	Data 6					Parity
Generation	Data 5	P parity	Q parity	Data 6	Data 7	P parity	Q parity	Data 8	Generation
	P parity	Q parity	Data 9	Data 10	P parity	Q parity	Data 11	Data 12
	Q parity	Data 13	Data 14	P parity	Q parity	Data 15	Data 16	P parity
	Drive 1	Drive 2	Drive 3	Drive 4	Drive 5	Drive 6	Drive 7	Drive 8

Figure 10. Example of RAID 60 (6 + 0)

Advantages of RAID 60

∙Allows creation of largest RAID groups, up to 256 drives (theoretical); large RAID volumes are allowed for up to 192 drives connected to PERC H800

∙High degree of fault tolerance due to 2 parity calculations being done for each RAID 6 subset

∙Medium-to-high write transaction rate

Disadvantages of RAID 60

∙One of the more complex RAID implementations

∙Less space-efficient than RAID 6 since separate parity calculations are done for each RAID 6 subset

∙Retrieval of parity information after a drive failure takes longer than using a mirrored solution

DELL PERC H700 and H800 Technical Guide

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Contents Dell PowerEdge RAID Controller Cards March Table of Contents Tables Appendix aProduct Comparison OverviewPerc H700 Overview Perc H700 Integrated Additional Sled for PCIe SlotPerc H800 Overview Perc H700 ModularPerc H800 Adapter New Features 6Gb/s SAS SAS 2.0 OverviewGb/s SAS SAS 2.0 Features 1 6Gb/s SAS Performance Benefit over 3Gb/s SAS2 6Gb/s SAS Expectation SAS Performance DetailsDell PowerEdge Server Support PowerEdge Server Support with Perc H700 and Perc H800Product Support Management Software SupportOperating System Support with Perc H700 and Perc H800 Drive SupportDrive Support Product Overview Perc H700 and Perc H800 FeaturesPerc H700 and Perc H800 Overview Power Management RAID Level CacheCade Reconfiguring Virtual DisksCut-Through IO Fault-Tolerance Features RAID Level MigrationNon-Volatile Cache Using Replace Member and Revertible Hot SparesAutomatic Replace Member with Predicted Failure Physical Disk Hot Swapping Battery Back-up of Controller CacheEnclosure Affinity Configuring and Managing Secured RAID Disk RoamingDisk Migration Perc H700 and H800 Security Key and RAID ManagementVirtual Disk Write Cache Policies Virtual Disk Read Cache PoliciesRAID 0 Striped Virtual Disk without Fault Tolerance RAID OverviewAbout RAID Advantages of RAIDRAID 1 Mirroring Example of RAID Advantages of RAIDRAID 5 Striping With Distributed Parity Example of RAID 1 MirroringRAID 6 Striping With Dual Distributed Parity DriveRAID 10 Striping over Mirrored Sets Example of RAID 6 Single Virtual Disk with 5 drivesRAID 50 Striping Across RAID Disadvantages of RAIDRAID 60 Striping Across RAID Example of RAID 50 5 + Advantages of RAIDExample of RAID 60 6 + Advantages of RAID Appendix A. Additional Resources Resource Contact Information and Descriptions