有关write consistency check的疑问

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183书上如是表述：There are, however, fewer partitions on a physical volume at the center than at the other regions (unless when mirrored with mirror write consistency check).
这里我不是很理解，是指mirrored with mirror write consistency check后，center的partition会增多吗？这是为什么？哪位高手回答一下，谢谢了
此外，这个smit选项应该就是对应mirrorvg中的-m吧