lvm的工作原理和特点是什么（lvm的讲解）

磁盘故障小案例

LVM

结构：PV->VG->LV

lvm的工作原理和特点是什么（lvm的讲解）(1)

默认系统未安装LVM工具：yum install -y lvm2

如何根据命令搜索安装包： yum provides "/*/COMMAND"

LVM创建步骤

PV -> VG -> LV

创建新分区，修改类型为8e（Linux LVM，必须设置)

[root@localhost ~]# fdisk /dev/sdb 欢迎使用 fdisk (util-linux 2.23.2)。更改将停留在内存中，直到您决定将更改写入磁盘。使用写入命令前请三思。 Device does not contain a recognized partition table 使用磁盘标识符 0x3d3ec47f 创建新的 DOS 磁盘标签。命令(输入 m 获取帮助)：n Partition type: p primary (0 primary, 0 extended, 4 free) e extended Select (default p): p 分区号 (1-4，默认 1)：起始扇区 (2048-20971519，默认为 2048)：将使用默认值 2048 Last 扇区, 扇区 or size{K,M,G} (2048-20971519，默认为 20971519)： 1G 分区 1 已设置为 Linux 类型，大小设为 1 GiB 命令(输入 m 获取帮助)：t 已选择分区 1 Hex 代码(输入 L 列出所有代码)：8e 已将分区“Linux”的类型更改为“Linux LVM” 命令(输入 m 获取帮助)：p 磁盘 /dev/sdb：10.7 GB, 10737418240 字节，20971520 个扇区 Units = 扇区 of 1 * 512 = 512 bytes 扇区大小(逻辑/物理)：512 字节 / 512 字节 I/O 大小(最小/最佳)：512 字节 / 512 字节磁盘标签类型：dos 磁盘标识符：0x3d3ec47f 设备 boot Start End Blocks Id System /dev/sdb1 2048 2099199 1048576 8e Linux LVM

有些情况下使用fdisk命令划分出来的磁盘分区，其对应的如/dev/sdb1这样的设备文件会找不到，需要执行partprobe命令来自动生成。

[root@localhost ~]# pvcreate /dev/sdb1 Device /dev/sdb1 not found (or ignored by filtering). [root@localhost ~]# partprobe [root@localhost ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created.

2. 创建物理卷PV

# pvcreate命令创建物理卷 [root@localhost ~]# pvcreate /dev/sdb1 Physical volume "/dev/sdb1" successfully created. # pvdisplay查看物理卷详细信息 [root@localhost ~]# pvdisplay "/dev/sdb1" is a new physical volume of "1.00 GiB" --- NEW Physical volume --- PV Name /dev/sdb1 VG Name PV Size 1.00 GiB Allocatable NO PE Size 0 Total PE 0 Free PE 0 Allocated PE 0 PV UUID iyXCTX-A91e-k0VO-oU3M-jhpo-iuGG-5QKAih # 也可以使用pvs简单查看 [root@localhost ~]# pvs PV VG Fmt Attr PSize PFree /dev/sdb1 lvm2 --- 1.00g 1.00g

3. 创建卷组：vgcreate vg1 pv1 [pv2...]

# 将/dev/sdb1和/dev/sdb2这2个物理卷创建为一个名为vg1的卷组 [root@localhost ~]# vgcreate vg1 /dev/sdb1 /dev/sdb2 Volume group "vg1" successfully created # vgdisplay查看卷组详细信息 # 2个1G大小的物理卷生成了1个2G大小的卷组 [root@localhost ~]# vgdisplay --- Volume group --- VG Name vg1 System ID Format lvm2 Metadata Areas 2 Metadata Sequence No 1 VG Access read/write VG Status resizable MAX LV 0 Cur LV 0 Open LV 0 Max PV 0 Cur PV 2 Act PV 2 VG Size 1.99 GiB PE Size 4.00 MiB Total PE 510 Alloc PE / Size 0 / 0 Free PE / Size 510 / 1.99 GiB VG UUID SoIBUl-69cj-pPdj-WBcq-ARdx-lym0-LF3iv2 # vgs简单查看 [root@localhost ~]# vgs VG #PV #LV #SN Attr VSize VFree vg1 2 0 0 wz--n- 1.99g 1.99g

4. 创建逻辑卷：lvcreate -L 100M -n lv1 vg1（lvdisplay查看卷组信息）

# 从卷组vg1中划分出一个100M大小的逻辑卷lv1，-L指定大小，-n指定名称 [root@localhost ~]# lvcreate -L 100M -n lv1 vg1 WARNING: ext4 signature detected on /dev/vg1/lv1 at offset 1080. Wipe it? [y/n]: y Wiping ext4 signature on /dev/vg1/lv1. Logical volume "lv1" created. # 查看创建好的lv1的详细信息 [root@localhost ~]# lvdisplay --- Logical volume --- LV Path /dev/vg1/lv1 LV Name lv1 VG Name vg1 LV UUID PDbLhq-fwuE-Kibx-Ahmv-49ki-4YFm-oC5QBX LV Write Access read/write LV Creation host, time localhost.localdomain, 2017-11-01 20:28:48 0800 LV Status available # open 0 LV Size 100.00 MiB Current LE 25 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 8192 Block device 253:0 # 简单查看 [root@localhost ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv1 vg1 -wi-a----- 100.00m

5. 格式化逻辑卷：mkfs.ext4 /dev/vg1/lv1

# 这个设备名是 /dev/卷组名/逻辑卷名 [root@localhost ~]# mkfs.ext4 /dev/vg1/lv1 mke2fs 1.42.9 (28-Dec-2013) 文件系统标签= OS type: Linux 块大小=1024 (log=0) 分块大小=1024 (log=0) Stride=0 blocks, Stripe width=0 blocks 25688 inodes, 102400 blocks 5120 blocks (5.00%) reserved for the super user 第一个数据块=1 Maximum filesystem blocks=33685504 13 block groups 8192 blocks per group, 8192 fragments per group 1976 inodes per group Superblock backups stored on blocks: 8193, 24577, 40961, 57345, 73729 Allocating group tables: 完成正在写入inode表: 完成 Creating journal (4096 blocks): 完成 Writing superblocks and filesystem accounting information: 完成

6. 挂载：mount /dev/vg1/lv1 /mnt

[root@localhost ~]# mount /dev/vg1/lv1 /mnt [root@localhost ~]# mount | tail -n 1 /dev/mapper/vg1-lv1 on /mnt type ext4 (rw,relatime,seclabel,data=ordered) [root@localhost ~]# df -h 文件系统容量已用可用已用% 挂载点 /dev/sda3 18G 1.2G 17G 7% / devtmpfs 479M 0 479M 0% /dev tmpfs 489M 0 489M 0% /dev/shm tmpfs 489M 6.7M 482M 2% /run tmpfs 489M 0 489M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 98M 0 98M 0% /run/user/0 /dev/mapper/vg1-lv1 93M 1.6M 85M 2% /mnt

使用df命令发现挂载的文件名称变为了 /dev/mapper/vg1-lv1 ，其实质上跟 /dev/vg1/lv1指向了同一个文件

[root@localhost ~]# ls -l /dev/vg1/lv1 /dev/mapper/vg1-lv1 lrwxrwxrwx. 1 root root 7 ... /dev/mapper/vg1-lv1 -> ../dm-0 lrwxrwxrwx. 1 root root 7 ... /dev/vg1/lv1 -> ../dm-0

逻辑卷扩/缩容

扩容逻辑卷(ext4格式)

先卸载：umount /mnt

[root@localhost ~]# umount /mnt

2. 重新设置逻辑卷大小：lvresize -L 200M /dev/vg1/lv1

[root@localhost ~]# lvresize -L 200M /dev/vg1/lv1 WARNING: Reducing active logical volume to 200.00 MiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce vg1/lv1? [y/n]: y Size of logical volume vg1/lv1 changed from 300.00 MiB (75 extents) to 200.00 MiB (50 extents). Logical volume vg1/lv1 successfully resized.

3. 磁盘错误检测：e2fsck -f /dev/vg1/lv1

[root@localhost ~]# e2fsck -f /dev/vg1/lv1 e2fsck 1.42.9 (28-Dec-2013) 第1步: 检查inode,块,和大小第2步: 检查目录结构第3步: 检查目录连接性 Pass 4: Checking reference counts 第5步: 检查簇概要信息 /dev/vg1/lv1: 11/25688 files (9.1% non-contiguous), 8896/102400 blocks

4. 更新逻辑卷信息至系统：resize2fs /dev/vg1/lv1

[root@localhost ~]# resizefs /dev/vg1/lv1 -bash: resizefs: 未找到命令 [root@localhost ~]# resize2fs /dev/vg1/lv1 resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/vg1/lv1 to 204800 (1k) blocks. The filesystem on /dev/vg1/lv1 is now 204800 blocks long.

5. 挂载：mount /dev/vg1/lv1

[root@localhost ~]# mount /dev/vg1/lv1 /mnt #验证是否成功增容 [root@localhost ~]# df -h 文件系统容量已用可用已用% 挂载点 /dev/sda3 18G 1.2G 17G 7% / devtmpfs 479M 0 479M 0% /dev tmpfs 489M 0 489M 0% /dev/shm tmpfs 489M 6.7M 482M 2% /run tmpfs 489M 0 489M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 98M 0 98M 0% /run/user/0 /dev/mapper/vg1-lv1 190M 1.6M 175M 1% /mnt

缩减逻辑卷（xfs不支持）

先卸载

[root@localhost ~]# umount /mnt

2. 检测磁盘错误信息

[root@localhost ~]# e2fsck -f /dev/vg1/lv1 e2fsck 1.42.9 (28-Dec-2013) 第1步: 检查inode,块,和大小第2步: 检查目录结构第3步: 检查目录连接性 Pass 4: Checking reference counts 第5步: 检查簇概要信息 /dev/vg1/lv1: 11/49400 files (9.1% non-contiguous), 11884/204800 blocks

3. 更新逻辑卷信息

[root@localhost ~]# resize2fs /dev/vg1/lv1 100M resize2fs 1.42.9 (28-Dec-2013) Resizing the filesystem on /dev/vg1/lv1 to 102400 (1k) blocks. The filesystem on /dev/vg1/lv1 is now 102400 blocks long.

4. 重置逻辑卷大小

[root@localhost ~]# lvresize -L 100M /dev/vg1/lv1 WARNING: Reducing active logical volume to 100.00 MiB. THIS MAY DESTROY YOUR DATA (filesystem etc.) Do you really want to reduce vg1/lv1? [y/n]: y Size of logical volume vg1/lv1 changed from 200.00 MiB (50 extents) to 100.00 MiB (25 extents). Logical volume vg1/lv1 successfully resized. [root@localhost ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv1 vg1 -wi-a----- 100.00m

5. 挂载逻辑卷

[root@localhost ~]# mount /dev/vg1/lv1 /mnt [root@localhost ~]# df -h 文件系统容量已用可用已用% 挂载点 /dev/sda3 18G 1.2G 17G 7% / devtmpfs 479M 0 479M 0% /dev tmpfs 489M 0 489M 0% /dev/shm tmpfs 489M 6.7M 482M 2% /run tmpfs 489M 0 489M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 98M 0 98M 0% /run/user/0 /dev/mapper/vg1-lv1 93M 1.6M 85M 2% /mnt

扩容逻辑卷（xfs)

前期准备：格式化lv1为xfs并挂载

[root@localhost ~]# umount /mnt [root@localhost ~]# mkfs.xfs -f /dev/vg1/lv1 meta-data=/dev/vg1/lv1 isize=512 agcount=4, agsize=6400 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=0, sparse=0 data = bsize=4096 blocks=25600, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal log bsize=4096 blocks=855, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 [root@localhost ~]# mount /dev/vg1/lv1 /mnt

2. 重置逻辑卷大小

[root@localhost ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv1 vg1 -wi-ao---- 100.00m [root@localhost ~]# lvresize -L 300M /dev/vg1/lv1 Size of logical volume vg1/lv1 changed from 100.00 MiB (25 extents) to 300.00 MiB (75 extents). Logical volume vg1/lv1 successfully resized. [root@localhost ~]# lvs LV VG Attr LSize Pool Origin Data% Meta% Move Log Cpy%Sync Convert lv1 vg1 -wi-ao---- 300.00m # 当前lv大小还未改变 [root@localhost ~]# df -h 文件系统容量已用可用已用% 挂载点 /dev/sda3 18G 1.2G 17G 7% / devtmpfs 479M 0 479M 0% /dev tmpfs 489M 0 489M 0% /dev/shm tmpfs 489M 6.7M 482M 2% /run tmpfs 489M 0 489M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 98M 0 98M 0% /run/user/0 /dev/mapper/vg1-lv1 97M 5.2M 92M 6% /mnt

3. 更新逻辑卷信息

[root@localhost ~]# xfs_growfs /dev/vg1/lv1 meta-data=/dev/mapper/vg1-lv1 isize=512 agcount=4, agsize=6400 blks = sectsz=512 attr=2, projid32bit=1 = crc=1 finobt=0 spinodes=0 data = bsize=4096 blocks=25600, imaxpct=25 = sunit=0 swidth=0 blks naming =version 2 bsize=4096 ascii-ci=0 ftype=1 log =internal bsize=4096 blocks=855, version=2 = sectsz=512 sunit=0 blks, lazy-count=1 realtime =none extsz=4096 blocks=0, rtextents=0 data blocks changed from 25600 to 76800 # 已成功扩容 [root@localhost ~]# df -h 文件系统容量已用可用已用% 挂载点 /dev/sda3 18G 1.2G 17G 7% / devtmpfs 479M 0 479M 0% /dev tmpfs 489M 0 489M 0% /dev/shm tmpfs 489M 6.7M 482M 2% /run tmpfs 489M 0 489M 0% /sys/fs/cgroup /dev/sda1 197M 109M 88M 56% /boot tmpfs 98M 0 98M 0% /run/user/0 /dev/mapper/vg1-lv1 297M 5.5M 292M 2% /mnt

扩展卷组

逻辑卷最大只能扩展到卷组那么大，当卷组空间用光时，可以通过扩展卷组的容量，再去扩展逻辑卷。