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
Array Configuration Utility (ACU)
102 Modular SAN Array 1000 User Guide
Controller Settings
The default controller settings provided by ACU are adequate for many purposes.
However, this task lets you alter the priority settings for array expansion and
rebuild. You can also disable the array accelerator (if one is present) or change the
ratio of read cache to write cache (if the controller has battery-backed cache).
To change the controller settings:
1. Click Controller Settings and click Begin.
The next two screens let you change the expand priority and the rebuild
priority settings. These settings determine how much importance you want an
array expansion or rebuild to have relative to normal I/O operations.
■ With low priority, the expansion or rebuild takes place only when the
array controller is not busy handling normal I/O requests. This setting has
minimal effect on normal I/O operations. However, there is an increased
risk that data will be lost if another physical drive fails while the rebuild is
in progress.
■ With high priority, the rebuild or expansion occurs at the expense of
normal I/O operations. Although system performance is affected, this
setting provides better data protection because the array is vulnerable to
additional drive failures for a shorter time.
■ At the medium priority setting, expansion or rebuild occurs for half of the
time, and normal I/O requests are handled during the rest of the time.
2. Set the expand priority to high, medium, or low; click Next.
3. Set the rebuild priority and click Next.
4. If the controller has an array accelerator, a screen is now displayed that lets
you disable it for particular logical drives.
Choose whether to disable the array accelerator for any logical drives and
click Next.
Note: Disabling the array accelerator for a particular logical drive reserves use of the
accelerator cache for other logical drives on the array that need to have maximum
possible performance (such as those that contain database information).
5. If the controller has a battery-backed cache, a screen is now displayed that lets
you change the read/write cache ratio.
Choose the ratio that you want the controller to use and click Next.
230941-005_MSA1000_UG.book Page 102 Thursday, April 17, 2003 5:53 PM