Dell H800, H700 manual 1 6Gb/s SAS Performance Benefit over 3Gb/s SAS, 2 6Gb/s SAS Expectation

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Other new features of the 6Gb/s SAS controllers will offer improved signal integrity and additional safeguards to enhance data protection with support for SED (Self-Encrypting Drive) technology.

Table 2. 6Gb/s SAS (SAS 2.0) Features

 

DAS-based

 

Server Storage

 

 

6Gb/s Throughput

 

 

3Gb/s Compatible

 

 

Standard Mini-SAS Connectors (SFF-8087

and SFF-8088)

 

 

 

DFE (Decision Feedback Equalization)

improved signaling

 

 

 

SSC (Spread Spectrum Clocking) reduced

radiated emissions

 

 

 

Enhanced Security with SED (Self-

Encrypting Drive) support

 

 

 

Improved Scalability

 

 

2.2.16Gb/s SAS Performance Benefit over 3Gb/s SAS

In small disk drive configurations (one to eight drives) the aggregate media rate of the disks (the speed at which the disk heads can read and write data) become the bottleneck for storage throughput. As business storage needs grow, IT centers can add more disk drives to their storage infrastructure, and the latest generation of SAS allows server performance to scale past the 3Gb/s SAS performance limitations: from 2.4 GB/s to 4.8 GB/s unidirectional.

Table 3. SAS Performance Details

SAS Generation

PCI-Express

Approximate number of SAS

 

Interface

HDDs required saturate

 

 

 

bandwidth (RAID 0)

 

 

 

1.0 (3Gb)

1.0

8 to10

 

 

 

2.0 (6Gb)

2.0

16 to 20

 

 

 

In addition to the improvements in the SAS bandwidth, PCI Express 2.0 provides double the system- to-storage controller interconnect speed. The x8 PCI Express 1.0 interface linking the controller to the host platform limited throughput even further to a theoretical 2GB/s maximum, that limitation has been raised to 4GB/s (unidirectional).

2.2.26Gb/s SAS Expectation

RAID controllers employing 6Gb/s SAS technology excel in both high IOP and high bandwidth applications. Applications and environments that benefit most range from traditional data center applications (such as random IOPs intensive email, web and database servers) to streaming and archival applications that will benefit from improved sequential read and write throughput. This means more users, more video streams, more email accounts, and faster backups are now possible.

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 Overview2 6Gb/s SAS Expectation Gb/s SAS SAS 2.0 Features1 6Gb/s SAS Performance Benefit over 3Gb/s SAS SAS Performance DetailsProduct Support Dell PowerEdge Server SupportPowerEdge Server Support with Perc H700 and Perc H800 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 Disk Migration Configuring and Managing Secured RAIDDisk Roaming Perc H700 and H800 Security Key and RAID ManagementVirtual Disk Write Cache Policies Virtual Disk Read Cache PoliciesAbout RAID RAID 0 Striped Virtual Disk without Fault ToleranceRAID Overview 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