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2.3. LVM 逻辑卷
在 LVM 中，卷组会被分成逻辑卷。LVM 逻辑卷有三种类型：线性卷、条状卷和镜像卷。这些在以后的内容中都有论述。
2.3.1. 线性卷
一个线性卷可将多个物理卷集合到一个逻辑卷中。例如：如果您有两个 60GB 的磁盘，您可以创建一个 120GB 的逻辑卷。物理存储是连在一起的。
Creating a linear volume assigns a range of physical extents to an area of a logical volume in order. For example, as shown in 图 2.2 “扩展映射” logical extents 1 to 99 could map to one physical volume and logical extents 100 to 198 could map to a second physical volume. From the point of view of the application, there is one device that is 198 extents in size.
图 2.2. 扩展映射
The physical volumes that make up a logical volume do not have to be the same size. 图 2.3 “物理卷大小不同的线性卷” shows volume group
VG1 with a physical extent size of 4MB. This volume group includes 2 physical volumes named PV1 and PV2. The physical volumes are divided into 4MB units, since that is the extent size. In this example, PV1 is 100 extents in size (400MB) and PV2 is 200 extents in size (800MB). You can create a linear volume any size between 1 and 300 extents (4MB to 1200MB). In this example, the linear volume named LV1 is 300 extents in size.
图 2.3. 物理卷大小不同的线性卷
You can configure more than one linear logical volume of whatever size you desire from the pool of physical extents. 图 2.4 “多逻辑卷” shows the same volume group as in 图 2.3 “物理卷大小不同的线性卷”, but in this case two logical volumes have been carved out of the volume group:
LV1, which is 250 extents in size (1000MB) and LV2 which is 50 extents in size (200MB).
图 2.4. 多逻辑卷
