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 ● 82
RAID 6 Arrays
A RAID 6 array—also known as dual drive failure protection—is similar to a RAID 5 array
because it uses data striping and parity data to provide redundancy. However, RAID 6 arrays
include two independent sets of parity data instead of one. Both sets of parity data are striped
separately across all disk drives in the array.
RAID 6 arrays provide extra protection for your data because they can recover from two
simultaneous disk drive failures. However, the extra parity calculation slows performance
(compared to RAID 5 arrays).
RAID 6 arrays must be built from at least four disk drives. Maximum stripe size depends on
the number of disk drives in the array.
RAID 60 Arrays
Similar to a RAID 50 array (see page 81), a RAID 60 array—also known as dual drive failure
protection—is built from eight disk drives configured as two or more RAID 6 arrays, and
stripes stored data and two sets of parity data across all disk drives in both RAID 6 arrays.
Note:
Because they support four disk drives only, the Adaptec 2420SA RAID controller can’t
support RAID 60 arrays.
Two sets of parity data provide enhanced data protection, and striping improves performance.
RAID 60 arrays also provide high data transfer speeds.
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 P1 ... P2
2 P2 ... 449
P1 3 ... P1
P2 4 ... 500
Unused Space = 150 GB
Disk Drives in Logical Drive Based on the drive segment sizes used:
RAID 6 Logical Drive = 500 GB plus
parity (P1 & P2)
Unused Space = 150 GB