Selecting an appropriate RAID Level according to Area of Application

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Requirements

When selecting an appropriate RAID level, the following question are often asked.

  • Which RAID level should I choose for the operating system?
  • Do I need RAID 10 for my database?
  • Is RAID 5 reasonable for my backup server?
  • ...

To answer these questions, determining the demand applied to the RAID array first will be helpful.

  • What are the capacity requirements (how much of the disks will be in use)?
  • What are the performance requirements (what levels of read and write performance will be required)?
  • What is the data redundancy requirement (how many hard disk can be allowed to fail without data loss)?

Overview of the Most Important RAID Levels

The following table provides a rough overview of the characteristics and potential application areas for the commonly used RAID levels. The information is an extract from the Adaptec whitepaper, Which RAID Level is Right for Me?[1].

Product Characteristic RAID 0 RAID 1 RAID 5 RAID 6 RAID 10
Min. Number of HDDs 2 2 3 4 4
Data Redundancy None Single-drive
failure
Single-drive
failure
Two-drive
failure
Failures of
one drive
per sub-array
Capacity in Use 100% 50% 67% - 94% 50% - 88% 50%
Typical Application
  • High performance
    workstations
  • Data
    logging
  • Real-time
    processing
  • data that changes often or is volatile
  • Operating system
  • Transactional databases
  • Data warehousing,
  • Web servers,
  • Archives
  • Data archives
  • Backup to disk
  • High-traffic solutions
  • Servers with high performance
    demands
  • Fast databases
  • Application servers

References

  1. Which RAID Level is Right for Me? (Adaptec Whitepaper)

Additional Information

  • RAID (en.wikipedia.org)

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