User guide
Table Of Contents
- MSA1000 User Guide
- Contents
- About this Guide
- Chapter 1: Introduction
- Chapter 2: Operating System Specific Information
- Chapter 3: MSA1000 Setup and Sample Configurations
- Chapter 4: Operation and Management
- Chapter 5: Array Configuration Utility (ACU)
- Installing the ACU on the Server
- Accessing the ACU
- Description of Screen Regions
- Configuring a New Controller
- Modifying an Existing Controller
- Probability of Logical Drive Failure
- Chapter 6: Command Line Interface (CLI)
- CLI Overview
- CLI Setup
- Help Commands
- Display Commands
- Array Controller Configuration Commands
- LUN Management Commands
- Server Connection Commands
- Selective Storage Presentation/Access Control List Commands
- Appendix A: Regulatory Compliance Notices
- Appendix B: Electrostatic Discharge
- Appendix C: Specifications
- Appendix D: Hard Drive Arrays
- Appendix E: Recovering from Hard Drive Failure
- Appendix F: Controller Display Messages
- Appendix G: Recovery ROM and ROM Cloning
- Appendix H: SCSI ID Assignments
- Index
Hard Drive Arrays
177Modular SAN Array 1000 User Guide
RAID 1 Drive Mirroring/RAID 1+0—Data Striping and Drive Mirroring
RAID 1 configurations contain only two drives. In this configuration, data is
duplicated to a second drive.
Figure 65: Drive mirroring of P1 to P2
When a RAID 1 array has more than two physical drives, this fault-tolerance
method is referred to as RAID 1+0. In this configuration, the data blocks are
striped across half of the drives in the array and then the drives are mirrored in
pairs. See Figure 66 for an illustration of this configuration method.
In each mirrored pair, the physical drive that is not busy answering other requests
answers any read request sent to the array. (This behavior is called load
balancing.) If a physical drive fails, the remaining drive in the mirrored pair can
still provide all the necessary data. Several drives in the array can fail without
incurring data loss, as long as no two failed drives belong to the same mirrored
pair.
This fault-tolerance method is useful when high performance and data protection
are more important than the cost of physical drives.
P1 P2
B1
B2
B3
B4
B1
B2
B3
B4
230941-005_MSA1000_UG.book Page 177 Thursday, April 17, 2003 5:53 PM