Adaptec 44300, 48300, 58300 RAID 1 Arrays, RAID 10 Arrays

Appendix B: Understanding RAID ●61

RAID 1 Arrays

A RAID 1 array is built from two disk drives, where one disk drive is a mirror of the other (the

same data is stored on each disk drive). Compared to independent disk drives, RAID 1 arrays

provide improved performance, with twice the read rate and an equal write rate of single disks.

However, capacity is only 50 percent of independent disk drives.

If the RAID 1 array is built from different-sized disk drives, the free space, drive segment size is

the size of the smaller disk drive, as shown in the following figure.

RAID 10 Arrays

A RAID 10 array is built from two or more equal-sized RAID 1 arrays. Adaptec RAID

controllers support a maximum number of 48 disk drives in a RAID 10 array.

Data in a RAID 10 array is both striped and mirrored. Mirroring provides data protection, and

striping improves performance.

Drive segment size is limited to the size of the smallest disk drive in the array. For instance, an

array with two 250 GB disk drives and two 400 GB disk drives can create two mirrored drive

segments of 250 GB, for a total of 500 GB for the array, as shown in the following figure.

Disk Drive 1Disk Drive 2250 GB400 GB

Disk Drives in Lo

g

ical Drive

Disk Drive 1Disk Drive 2

RAID 1 Lo

g

ical Drive = 250 GB

Not Used Unused Space: 150 GB1 – 2501 – 250Drive Segment Size (Smaller Disk Drive)

Disk Drive 1

Disk Drive 2

Disk Drive 3

Disk Drive 4

250 GB

250 GB

400 GB

400 GB

Disk Drives in Logical Drive

Disk Drive 1

Disk Drive 2

Disk Drive 3

Disk Drive 4

RAID 10 Lo

g

ical Drive = 500 GB

1

2

1

2

Not Used

Not Used

3

4

3

4500

499

500

499

...

...

...

...

Unused Space: 150 GB

Unused Space: 150 GB

Drive Segment Size (Smallest Disk Drive)

Contents

Main Page Adaptec Customer Support Limited 3-Year Hardware Warranty Regulatory Compliance Statements Australian/New Zealand Compliance Statement Canadian Compliance Statement Japanese Compliance (Voluntary Control Council Initiative) Contents Page Understanding Adaptec Storage Manager Solving Problems Introduction to SAS Understanding RAID Using the ARC Utility Using the AFU for DOS Safety Information Technical Specifications About This Guide What You Need to Know Before You Begin Terminology Used in this Guide How to Find More Information About Your HostRAID Controller HostRAID Controller Features Array Level Features Upgrading the HostRAID Controller Firmware About the Adaptec SAS 58300 Controller The Adaptec SAS 58300 is a low-profile PCI-X to 8-Phy SAS 1.0 HostRAID controller with About the Adaptec SAS 48300 Controller The Adaptec SAS 48300 is a low-profile PCI-X to 8-Phy SAS 1.0 HostRAID controller with About the Adaptec SAS 44300 Controller The Adaptec SAS 44300 is a low-profile PCI-X to 4-Phy SAS 1.0 HostRAID controller with Page Kit Contents System Requirements Getting Started Choosing a RAID Level Selecting Disk Drives Disk Drives for Your Controller Selecting Cables SAS Cables Installation Options Basic Installation Steps Installing with an Operating System Page Page Installing the HostRAID Controller Connecting Disk Drives to HostRAID Controllers Connecting Directly to the HostRAID Controller Connecting to a System Backplane Installing the Controller to a SAS Expander Next Steps Creating a Bootable Array Setting the Boot Controller Creating an Array Creating an Array with the ACU Creating an Array with Adaptec Storage Manager Making Your Array Bootable Installing the Driver and an Operating System Creating a Driver Disk Installing with Windows Installing with Red Hat Linux Installing with SuSE Linux Installing with NetWare Installing with SCO OpenServer Page Creating a Driver Disk Installing on Windows Installing on Red Hat or SuSE Linux Installing on NetWare Installing with SCO OpenServer Managing Your Storage Space About Adaptec Storage Manager Installing Adaptec Storage Manager About the HRCONF Command Line Utility About the ARC Utility About the AFU Which Utility Should I Use? Page Feature s Overview Physical Devices View Logical Devices View Changing How Drives are Displayed Chapter 10: Understanding Adaptec Storage Manager Collapsed and Expanded Views Component Views Page Troubleshooting Checklist Recovering from a Disk Drive Failure Failed Disk Drive Protected by a Hot Spare Failed Disk Drive Not Protected by a Hot Spare Failure in Multiple Arrays Simultaneously Disk Drive Failure in a RAID 0 Array Multiple Failures in the Same Array A Introduction to SAS Terminology Used in This Chapter What is SAS? How Do SAS Devices Communicate? Whats a Phy? Whats a SAS Port? Whats a SAS Address? Whats a SAS Connector? What do SAS Cables Look Like? How are Disk Drives Identified in SAS? What are the SAS Connection Options? Direct-attach Connections Backplane Connections SAS Expander Connections Appendix A: Introduction to SAS How is SAS Different from Parallel SCSI? SAS DomainSAS Domain B Understanding RAID RAID Technology Overview Understanding Drive Segments Stripe-unit Size Selecting a RAID Level and Tuning Performance Appendix B: Understanding RAID RAID 0 (Non-RAID Arrays) Appendix B: Understanding RAID RAID 1 Arrays Disk Drives in Logical Drive Not Used Unused Space: 150 GB g RAID 10 Arrays Using the ARC Utility Introduction to the ARC Utility Running the ARC Utility Creating and Managing Arrays Creating a New Array Page Managing Arrays Adding/Deleting Hotspares Managing Bootable Arrays and Devices Configuring Disk Drives Using SerialSelect you made in Seri alSelect take effect after the computer restarts. SerialSelect Options Formatting and Verifying Disk Drives D Using the AFU for DOS Introduction System Requirements Compatibility Running the AFU from the GUI Running the AFU from the Command Line HELP LIST SAVE UPDATE VERIFY VERSION Command Switches AFU Command Line Step-by-Step Page E Safety Information Electrostatic Discharge (ESD) Page Page Glossary A B C D E F H I L M N O P R S T V Index A B D E P R S T U