This is accomplished by having an exception list that is updated every time something changes between the LVs (formally known as CoW, Copy-on-Write).

快照由一个例外列表(exception list)来实现，每当LV之间出现差异时就会更新这个列表(正式的说法是CoW,Copy - on - Write)。

youdao

Copy-on-write (or COW) is a technique to delay or altogether prevent copying of the data.

即写即拷(或牛)技术完全延迟或防止复制的数据。

youdao

Copy-on-write (or COW) is a technique to delay or altogether prevent copying of the data.

即写即拷(或牛)技术完全延迟或防止复制的数据。

youdao