User guide
Table Of Contents
- Title Page
- Table of Contents
- About this User Guide
- Introducing the 3ware® SATA RAID Controller
- Getting Started with Your 3ware RAID Controller
- First-Time RAID Configuration Using 3BM
- Driver Installation
- Driver Installation Under Windows
- Driver Installation Under Linux
- Obtaining 3ware Linux Drivers
- Driver Installation Under Red Hat Linux or Fedora Core 5
- Materials required
- Creating a Red Hat Linux Driver Diskette
- Installing the 3ware Kernel Driver Module while Installing Red Hat Linux on a New Unit
- Installing the 3ware Kernel Driver Module on a Red Hat or Fedora Core Linux System that Boots From a Different Device
- About Variables In the Kernel Driver Module Installation Instructions
- Driver Installation Under SuSE Linux
- Compiling a 3ware Driver for Linux
- Driver Installation Under FreeBSD
- 3ware BIOS Manager 2 (3BM 2) Introduction
- 3DM 2 (3ware Disk Manager) Introduction
- Configuring Your Controller
- Configuring Units
- Configuring a New Unit
- Creating a Hot Spare
- Naming a Unit
- Setting Unit Policies
- Changing An Existing Configuration by Migrating
- Deleting a Unit
- Removing a Unit
- Moving a Unit from One Controller to Another
- Adding a Drive
- Removing a Drive
- Rescanning the Controller
- Maintaining Units
- Checking Unit and Drive Status through 3DM
- About Degraded Units
- About Inoperable Units
- Alarms, Errors, and Other Events
- Background Tasks
- Scheduling Background Tasks
- Locating a Drive by Blinking Its LED
- Maintaining Your Controller
- Determining the Current Version of Your 3ware Driver
- Updating the Firmware and Driver
- Downloading the Driver and Firmware
- Updating the Firmware Through 3DM 2
- Updating the 3ware Driver and Firmware Under Windows
- Using the Update Utility With Multiple Controllers
- Updating the 3ware Driver Under Windows XP
- Updating the 3ware Driver Under Red Hat or Fedora Core
- Updating the 3ware Driver Under SuSE
- Updating the 3ware Driver Under FreeBSD
- Updating the Firmware Under Linux and FreeBSD
- Viewing Battery Information
- Testing Battery Capacity
- 3DM 2 Reference
- Troubleshooting
- Appendices
- Index
Setting Unit Policies
www.3ware.com 113
• FUA (Force Unit Access). FUA commands are a way that the RAID
controller or a program (such as a database program) can ensure that data
is actually written to the disk drive media, and is not stored in cache.
When a write command is followed with a FUA command, then the disk
drive will only issue “command complete” to the controller once the data
is written to media. When performance is considered more important than
protection, it may be desirable to ignore FUA commands.
The Protection and Balanced profiles honor FUA commands if no BBU is
present; the Performance profile ignores them regardless of whether a
BBU is present.
If you use a battery backup unit (BBU), FUA is ignored, because the BBU
preserves the contents of the controller cache memory for a limited period
of time (up to 72 hours), in the event of a power failure.
•
Write Journaling. Write journaling tracks the writing of data to disk and
preserves a copy of data that has not yet been written to the disk media.
Following a power failure or in the event of accidental drive removal and
reinsertion, the firmware can recover the unit without data loss. All
pending writes sitting in the controller cache are replayed after power is
restored or the drive is reinserted and are flushed from the controller to
the drive.
Using write journaling helps protect your data, however it can have an
impact on performance.
Table 9: StorSave Profile Definitions
Protection (Default) Balanced Performance
Definition
Maximum data
protection, but slower
performance.
More data protection than
Performance but less
data protection than
Protection.
Maximum performance
for the unit, but less data
protection.
FUA (Force Unit
Access)
Honor FUA (If no BBU is
present)
Ignore FUA (If BBU is
present)
Honor FUA (If no BBU is
present)
Ignore FUA (If BBU is
present)
Ignore FUA
Write Journaling
Enabled Disabled, if no BBU
present. (Enabled, if BBU
is present.)
Disabled (If BBU is
present, this essentially
disables the BBU for this
unit.)
Disable Cache on
Degrade
Enabled Disabled Disabled