User`s guide
Table Of Contents
- About This Guide
- Kit Contents and System Requirements
- About Your RAID Controller
- Standard RAID Controller Features
- Adding Enhanced Features
- Adding a Battery Backup Module
- Upgrading the Controller Firmware
- About the Adaptec 3085
- About the Adaptec 3405
- About the Adaptec 3805
- About the Adaptec 31205
- About the Adaptec 31605
- About the Adaptec 4000
- About the Adaptec 4800SAS
- About the Adaptec 4805SAS
- About the Adaptec 2420SA
- About the Adaptec 2820SA
- About the Adaptec 2130SLP
- About the Adaptec 2230SLP
- Getting Started
- Installing the Controller and Disk Drives
- Creating a Bootable Array
- Installing the Driver and an Operating System
- Installing the Driver on an Existing Operating System
- Managing Your Storage Space
- Solving Problems
- Introduction to Serial Attached SCSI
- Understanding RAID
- Using the Adaptec RAID Configuration Utility
- Using the Array Configuration Utility for DOS
- Using the Adaptec Flash Utility
- Adaptec Serial Controller LED and I2C Connector Reference
- Adaptec 2420SA Activity LED and I2C Connector Specification
- Adaptec 2820SA Activity LED and I2C Connector Specification
- Adaptec 3085 LED and I2C Connector Specification
- Adaptec 3405 LED and I2C Connector Specification
- Adaptec 3805 LED and I2C Connector Specification
- Adaptec 31205 LED and I2C Connector Specification
- Adaptec 31605 LED and I2C Connector Specification
- Adaptec 4800SAS LED and I2C Connector Specification
- Adaptec 4805SAS LED and I2C Connector Specification
- Safety Information
- Technical Specifications
- Index
Appendix B: Understanding RAID ● 76
Understanding Drive Segments
A drive segment is a disk drive or portion of a disk drive that is used to create an array. A disk
drive can include both RAID segments (segments that are part of an array) and available
segments. Each segment can be part of only one logical device at a time. If a disk drive is not
part of any logical device, the entire disk is an available segment.
Non-redundant Arrays (RAID 0)
An array with RAID 0 includes two or more disk drives and provides data striping, where data
is distributed evenly across the disk drives in equal-sized sections. However, RAID 0 arrays do
not maintain redundant data, so they offer no data protection.
Compared to an equal-sized group of independent disks, a RAID 0 array provides improved I/O
perfor
mance.
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 a RAID 0 drive
segment of 250 GB, for a total of 1000 GB for the volume, as shown in this figure.
Disk Drive 1
Disk Drive 2
Disk Drive 3
Disk Drive 4
250 GB
250 GB
400 GB
400 GB
Drive Segment Size
(Smallest Disk Drive)
Disk Drive 2
Disk Drive 3
Disk Drive 4
Disk Drive 1
1 5 ... 997
26...998
3 7 ... 999
4 8 ... 1000
Unused Space = 150 GB
Disk Drives in Logical Drive RAID 0 Logical Drive = 1000 GB
Unused Space = 150 GB