RAID Intro

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RAID

stands for Redundant Array of Inexpensive Disks(廉价磁盘冗余阵列)

  • Hardware RAID

    Hardware RAID using controllers or RAID cards to manage the RAID configuration independently from the operating system.

  • Software RAID

    Software RAID tends to be slower than hardware RAID.

RAID Level Comparision

  • RAID 0
    raid 0

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    > data are split up into blocks that get written across all the drivers in the array. By using multiple disks (at least 2) at the same time, this offers fast read and write speeds.
    # Downside
      - RAID 0 is not redundant, the loss of any individual will cause complete data loss.

  • RAID 1
    raid 1

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    RAID 1 is setup of at least two drives.
    RAID 1 is high read performance, as data can be read off any of the drives in the array.
    Since the data needs to be written to all the drives in the array, the write speed is slower than a RAID 0 array.

  • RAID 5
    raid 5

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    "parity" distributed across the drives.
    READ speed is very fast but write speed is somewhat slower due to the partity that has to be calculated.

  • RAID 6
    raid 6

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    Read speed is as fast as RAID 5, but write speed is slower than RAID 5.
    RAID 6 is a very good option for a standard web server, where most of the transactions are reads, but its not recommanded for a heavy write environment.

  • RAID 10
    raid 10

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    RAID 10 can provide the speed of RAID 0 with the redundancy of RAID 1.
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chyiyaqing in ~ at chyiyaqing-PowerEdge-R720
➜ cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 02 Id: 00 Lun: 00
  Vendor: DELL     Model: PERC H710        Rev: 3.13
  Type:   Direct-Access                    ANSI  SCSI revision: 05

参考资料

raid level