2012年11月2日星期五

What is RAID? 什么是RAID?

RAID

RAID stands for Redundant Array of Inexpensive (Independent) Disks

In most situations you will be using one of the following four levels of RAIDs.

  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 10 (also known as RAID 1+0)
This article explains the main difference between these raid levels along with an easy to understand diagram.

In all the diagrams mentioned below:
  • A, B, C, D, E and F – represents blocks
  • p1, p2, and p3 – represents parity.

RAID LEVEL 0

Following are the key points to remember for RAID level 0.

  • Minimum 2 disks.
  • Excellent performance ( as blocks are striped ).
  • No redundancy ( no mirror, no parity ).
  • Don’t use this for any critical system.




RAID LEVEL 1

Following are the key points to remember for RAID level 1.

  • Minimum 2 disks.
  • Good performance ( no striping. no parity ).
  • Excellent redundancy ( as blocks are mirrored ).




RAID LEVEL 5

Following are the key points to remember for RAID level 5.

  • Minimum 3 disks.
  • Good performance ( as blocks are striped ).
  • Good redundancy ( distributed parity ).
  • Best cost effective option providing both performance and redundancy. Use this for DB that is heavily read oriented. Write operations will be slow.



RAID LEVEL 10 (1+0)
Following are the key points to remember for RAID level 10.

  • Minimum 4 disks.
  • This is also called as “stripe of mirrors”
  • Excellent redundancy ( as blocks are mirrored )
  • Excellent performance ( as blocks are striped )
  • If you can afford the dollar, this is the BEST option for any mission critical applications (especially databases).





RAID


RAID来至Redundant Array of Inexpensive (Independent) Disks

在大多数情况下,您将使用以下四个级别的RAID。

  • RAID 0
  • RAID 1
  • RAID 5
  • RAID 10 (also known as RAID 1+0)
这篇文章解释了这些RAID级别之间的主要区别,以及一个易于理解的图表。

在下面提及的所有图:
  • A,B,C,D,E和F - 代表块/资料
  • P1,P2,和p3 - 代表奇偶校验/资料结合

RAID LEVEL 0


下面是一些关键点要记住的RAID级别为0。

  • 最少2个磁盘。
  • 优异的性能(如块条带化)。
  • 不再备有冗余(无反光镜,无奇偶校验)。
  • 不要使用任何重要的系统。




RAID LEVEL 1


以下是关键点要记住的RAID级别1。


  • 最少2个磁盘。
  • 表现良好(没有条纹,无奇偶校验)。
  • 出色的冗余(以块的镜像)。




RAID LEVEL 5


下面是一些关键点要记住的RAID5级。


  • 最少3个磁盘。
  • 表现良好(块条带化)。
  • 良好的冗余性(分布式奇偶校验)。
  • 最佳成本效益的选择,同时提供性能和冗余。使用此DB,大量阅读导向。写操作将是缓慢的。



RAID LEVEL 10 (1+0)

下面是一些关键点要记住的RAID级别10。
  • 最少4个磁盘。
  • 这也被称为“条纹镜”
  • 出色的冗余(如块镜像)
  • 出色的性能(块条带化)
  • 如果你能负担得起的美元,这是任何关键任务的应用程序(尤其是数据库)的最佳选择。

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