Choosing RAID level for your SAN

The below chart gives an overview of the strong and weak points of each RAID level. I would summarise this as

  • RAID5 – Choose when you want to maximise capacity. Only suitable for small installations
  • RAID6 – A slightly more fault tolerant version of the RAID5 with slightly less capacity
  • RAID10 – When performance is paramount and you have lots of spare disks.
  • RAID50 – Suited to most deployments. A good balance of performance and capacity.

Workload Requirement

RAID10

RAID50

RAID6 (or60)

RAID5

Capacity

Poor

Good

Good

Best

Sequential Writes

Best

Best

Best

Best

Random Reads

Best

Best

Best

Best

Random Writes

Best

Good

Poor

Poor

Availability

Best

Good

Best

Poor

Performance impact of drive failure

Least

Moderate

Heavy

Heavy

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