RAID10与RAID01

sunyeait

RAID10与RAID01
RAID10~RAID0+1~RAID0+RAID1
RAID01~RAID1+0~RAID1+RAID0
如果对2n(n>=2)作镜像，系统将自动执行RAID1+0
一点解释：
RAID 0+1 - using 4 drives, two pairs are striped, and the results mirror each other. In this configuration, when one of the drives fails, it actually breaks the stipe that it belongs to, which in turn breaks the mirror... at this point, all you have is 1 stipe. At this point, if one drive fails, you are in trouble. To recover, the offending drive is removed, and the entire stipe needs to be resync'd.
RAID 1+0 - using 4 drives, two pairs are mirrored, and the results are used to create a single stripe. In this configuration, when one of the drives fails, it only breaks one mirror, without affecting the stripe... at this point, only 1/2 of the stipe is mirrored... but if a 2nd drive failure were to occur, it has a 2-in-3 chance of occuring on the last mirror... if it does, you are still OK. To recover, the offending drive is removed, and only the mirror of 1/2 the stripe needs to be resync'd.
举例说明：
raid 1+0
A1=B1
A2=B2
A=A1+A2
B=B1+B2
当A1坏时，B1再坏整个RAID完蛋，几率为1/3
raid 0+1
A=A1+A2
B=B1+B2
A=B
当A1坏时，A即坏但是同时B坏任何一块整个RAID都完蛋，几率为2/3
所以1+0好于O+1


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