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272 lines
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272 lines
9.3 KiB
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[#]: subject: "Add storage with LVM"
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[#]: via: "https://opensource.com/article/21/9/add-storage-lvm"
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[#]: author: "Ayush Sharma https://opensource.com/users/ayushsharma"
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[#]: collector: "lujun9972"
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[#]: translator: "perfiffer"
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[#]: reviewer: "wxy"
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[#]: publisher: "wxy"
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[#]: url: "https://linux.cn/article-14080-1.html"
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使用 LVM 添加存储
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======
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> LVM 为你配置存储的方式提供了极大的灵活性。
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<ruby>逻辑卷管理器<rt>Logical Volume Manager</rt></ruby>（LVM）允许在操作系统和硬件之间建立一个抽象层。通常，你的操作系统会查找磁盘（`/dev/sda`、`/dev/sdb` 等）和这些磁盘中的分区（`/dev/sda1`、`/dev/sdb1` 等）。
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LVM 在操作系统和磁盘之间创建了一个虚拟层。LVM 不是一个驱动器持有一定数量的分区，而是创建一个统一的存储池（称为<ruby>卷组<rt>Volume Group</rt></ruby>），跨越任意数量的物理驱动器（称为<ruby>物理卷<rt>Physical Volume</rt></ruby>）。使用卷组中可用的存储，LVM 可以为你的操作系统提供类似磁盘和分区的功能。
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操作系统完全没有意识到它被“欺骗”了。
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![Drive space][2]
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由于 LVM 虚拟地创建卷组和逻辑卷，因此即使在系统运行时，也可以轻松调整它们的大小或移动它们，或者创建新卷。此外，LVM 提供了其它情况下不存在的特性，比如创建逻辑卷的活动快照时无需首先卸载磁盘。
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LVM 中的卷组是一个命名的虚拟容器，将底层物理磁盘组合在一起。它充当一个池，可以从中创建不同大小的<ruby>逻辑卷<rt>Logical Volume</rt></ruby>。逻辑卷包含实际的文件系统并且可以跨越多个磁盘，并且不需要物理上连续。
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### 特性
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* 分区名称通常具有系统名称，例如 `/dev/sda1`。LVM 具有便于人们理解的名称，例如 `home` 或者 `media`。
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* 分区的总大小受底层物理磁盘大小的限制。在 LVM 中，卷可以跨越多个磁盘，并且仅受 LVM 中所有物理磁盘总大小的限制。
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* 分区通常只有在磁盘未使用且已卸载时才能调整大小、移动或删除。LVM 卷可以在系统运行时进行操作。
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* 只能通过分配与分区相邻的可用空间来扩展分区。LVM 卷可以从任何地方占用可用空间。
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* 扩展分区涉及移动数据以腾出可用空间，这非常耗时，并且可能会在断电期间导致数据丢失。LVM 卷可以从卷组中的任何地方占用可用空间，甚至可以在另一块磁盘上。
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* 因为在 LVM 中创建卷非常容易，所以它鼓励创建不同的卷，例如创建单独的卷来测试功能或尝试不同的操作系统。对于分区，此过程将非常耗时并且容易出错。
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* 快照只能在 LVM 中创建。它允许你创建当前逻辑卷的时间点镜像，即使在系统运行时也可以。这非常适合备份。
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### 测试设置
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作为演示，假设你的系统具有以下驱动器配置：
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```
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NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
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xvda 202:0 0 8G 0 disk
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`-xvda1 202:1 0 8G 0 part /
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xvdb 202:16 0 1G 0 disk
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xvdc 202:32 0 1G 0 disk
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xvdd 202:48 0 2G 0 disk
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xvde 202:64 0 5G 0 disk
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xvdf 202:80 0 8G 0 disk
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```
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#### 步骤 1. 初始化磁盘以用于 LVM
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运行 `pvcreate /dev/xvdb /dev/xvdc /dev/xvdd /dev/xvde /dev/xvdf`。输出应如下：
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```
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Physical volume "/dev/xvdb" successfully created
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Physical volume "/dev/xvdc" successfully created
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Physical volume "/dev/xvdd" successfully created
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Physical volume "/dev/xvde" successfully created
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Physical volume "/dev/xvdf" successfully created
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```
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使用 `pvs` 或者 `pvdisplay` 查看结果：
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```
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"/dev/xvde" is a new physical volume of "5.00 GiB"
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--- NEW Physical volume ---
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PV Name /dev/xvde
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VG Name
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PV Size 5.00 GiB
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Allocatable NO
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PE Size 0
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Total PE 0
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Free PE 0
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Allocated PE 0
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PV UUID 728JtI-ffZD-h2dZ-JKnV-8IOf-YKdS-8srJtn
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"/dev/xvdb" is a new physical volume of "1.00 GiB"
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--- NEW Physical volume ---
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PV Name /dev/xvdb
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VG Name
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PV Size 1.00 GiB
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Allocatable NO
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PE Size 0
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Total PE 0
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Free PE 0
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Allocated PE 0
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PV UUID zk1phS-7uXc-PjBP-5Pv9-dtAV-zKe6-8OCRkZ
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"/dev/xvdd" is a new physical volume of "2.00 GiB"
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--- NEW Physical volume ---
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PV Name /dev/xvdd
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VG Name
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PV Size 2.00 GiB
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Allocatable NO
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PE Size 0
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Total PE 0
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Free PE 0
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Allocated PE 0
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PV UUID R0I139-Ipca-KFra-2IZX-o9xJ-IW49-T22fPc
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"/dev/xvdc" is a new physical volume of "1.00 GiB"
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--- NEW Physical volume ---
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PV Name /dev/xvdc
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VG Name
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PV Size 1.00 GiB
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Allocatable NO
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PE Size 0
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Total PE 0
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Free PE 0
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Allocated PE 0
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PV UUID FDzcVS-sq22-2b13-cYRj-dXHf-QLjS-22Meae
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"/dev/xvdf" is a new physical volume of "8.00 GiB"
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--- NEW Physical volume ---
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PV Name /dev/xvdf
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VG Name
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PV Size 8.00 GiB
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Allocatable NO
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PE Size 0
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Total PE 0
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Free PE 0
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Allocated PE 0
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PV UUID TRVSH9-Bo5D-JHHb-g0NX-8IoS-GG6T-YV4d0p
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```
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#### 步骤 2. 创建卷组
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运行 `vgcreate myvg /dev/xvdb /dev/xvdc /dev/xvdd /dev/xvde /dev/xvdf`。通过 `vgs` 或者 `vgdisplay` 查看结果：
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```
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--- Volume group ---
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VG Name myvg
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System ID
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Format lvm2
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Metadata Areas 5
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Metadata Sequence No 1
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VG Access read/write
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VG Status resizable
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MAX LV 0
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Cur LV 0
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Open LV 0
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Max PV 0
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Cur PV 5
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Act PV 5
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VG Size 16.98 GiB
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PE Size 4.00 MiB
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Total PE 4347
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Alloc PE / Size 0 / 0
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Free PE / Size 4347 / 16.98 GiB
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VG UUID ewrrWp-Tonj-LeFa-4Ogi-BIJJ-vztN-yrepkh
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```
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#### 步骤 3: 创建逻辑卷
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运行以下命令：
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```
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lvcreate myvg --name media --size 4G
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lvcreate myvg --name home --size 4G
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```
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使用 `lvs` 或者 `lvdisplay` 验证结果：
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```
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--- Logical volume ---
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LV Path /dev/myvg/media
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LV Name media
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VG Name myvg
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LV UUID LOBga3-pUNX-ZnxM-GliZ-mABH-xsdF-3VBXFT
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LV Write Access read/write
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LV Creation host, time ip-10-0-5-236, 2017-02-03 05:29:15 +0000
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LV Status available
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# open 0
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LV Size 4.00 GiB
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Current LE 1024
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Segments 1
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Allocation inherit
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Read ahead sectors auto
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- currently set to 256
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Block device 252:0
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--- Logical volume ---
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LV Path /dev/myvg/home
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LV Name home
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VG Name myvg
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LV UUID Hc06sl-vtss-DuS0-jfqj-oNce-qKf6-e5qHhK
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LV Write Access read/write
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LV Creation host, time ip-10-0-5-236, 2017-02-03 05:29:40 +0000
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LV Status available
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# open 0
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LV Size 4.00 GiB
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Current LE 1024
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Segments 1
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Allocation inherit
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Read ahead sectors auto
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- currently set to 256
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Block device 252:1
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```
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#### 步骤 4: 创建文件系统
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使用以下命令创建文件系统：
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```
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vgcreate myvg /dev/xvdb /dev/xvdc /dev/xvdd /dev/xvde /dev/xvdf
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mkfs.ext3 /dev/myvg/media
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mkfs.ext3 /dev/myvg/home
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```
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挂载它：
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```
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mount /dev/myvg/media /media
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mount /dev/myvg/home /home
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```
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使用 `lsblk` 命令查看完整配置：
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```
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NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
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xvda 202:0 0 8G 0 disk
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`-xvda1 202:1 0 8G 0 part /
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xvdb 202:16 0 1G 0 disk
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xvdc 202:32 0 1G 0 disk
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xvdd 202:48 0 2G 0 disk
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xvde 202:64 0 5G 0 disk
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`-myvg-media 252:0 0 4G 0 lvm /media
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xvdf 202:80 0 8G 0 disk
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`-myvg-home 252:1 0 4G 0 lvm /home
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```
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#### 步骤 5: 扩展 LVM
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添加一块新的 `/dev/xvdg` 磁盘。要扩展 `home` 卷，运行以下命令：
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```
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pvcreate /dev/xvdg
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vgextend myvg /dev/xvdg
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lvextend -l 100%FREE /dev/myvg/home
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resize2fs /dev/myvg/home
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```
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运行 `df -h`，你应该可以看到新的磁盘大小。
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就是这样！
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LVM 为你配置存储的方式提供了极大的灵活性。尝试一下，并享受 LVM 的乐趣！
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本文首发于 [作者个人博客][4]，经授权改编。
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/21/9/add-storage-lvm
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作者：[Ayush Sharma][a]
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选题：[lujun9972][b]
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译者：[perfiffer](https://github.com/perfiffer)
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校对：[wxy](https://github.com/wxy)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]: https://opensource.com/users/ayushsharma
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[b]: https://github.com/lujun9972
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[1]: https://opensource.com/sites/default/files/styles/image-full-size/public/lead-images/bus-storage.png?itok=95-zvHYl (Storage units side by side)
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[2]: https://opensource.com/sites/default/files/lvm.png (Drive space)
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[3]: https://creativecommons.org/licenses/by-sa/4.0/
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[4]: https://notes.ayushsharma.in/2017/02/working-with-logical-volume-manager-lvm
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