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
181Modular SAN Array 1000 User Guide
Table 18: Summary of RAID Methods
RAID 0 RAID1+0 RAID 5 RAID ADG*
Alternative
name
Striping (no
fault
tolerance)
Striping and
Mirroring
Distributed
Data
Guarding
Advanced
Data
Guarding
Usable drive
space**
100% 50% 67% to 93% 50% to 96%
Usable drive
space formula
n n/2 (n-1)/n (n-2)/n
Minimum
number of
physical drives
1234
Tolerates
physical drive
failure?
No Yes Yes Yes
Tolerates
simultaneous
failure of
more than one
physical
drive?
No Only if no two
failed drives
are in a
mirrored pair
No Yes
Read
performance
High High High High
Write
performance
High Medium Low High
Relative cost Low High Medium Medium
* Not all controllers support RAID ADG.
** Values for usable drive space are calculated with these assumptions: (1) all
physical drives in the array have the same capacity; (2) online spares are not used;
(3) no more than 14 physical drives are used per array for RAID 5; (4) no more than
56 drives are used with RAID ADG.
230941-005_MSA1000_UG.book Page 181 Thursday, April 17, 2003 5:53 PM