LVM

1. 基础概念

  LVM利用Linux内核的device-mapper来实现存储系统的虚拟化(系统分区独立于底层硬件)。 通过LVM,你可以实现存储空间的抽象化并在上面建立虚拟分区(virtual partitions),可以更简便地扩大和缩小分区,可以增删分区时无需担心某个硬盘上没有足够的连续空间。
  LVM的基本组成块(building blocks)如下:

  • 物理卷Physical volume (PV):可以在上面建立卷组的媒介,可以是硬盘分区,也可以是硬盘本身或者回环文件(loopback file)。物理卷包括一个特殊的header,其余部分被切割为一块块物理区域(physical extents)。

  • 卷组Volume group (VG):将一组物理卷收集为一个管理单元。

  • 逻辑卷Logical volume (LV):虚拟分区,由物理区域(physical extents)组成。

  • 物理区域Physical extent (PE):硬盘可供指派给逻辑卷的最小单位(通常为4MB)。

  • 逻辑存储单元logical extent(LE):
    PE是物理存储单元,而LE则是逻辑存储单元,也即为lv中的逻辑存储单元,和pe的大小是一样的。从vg中划分lv,实际上是从vg中划分vg中的pe,只不过划分lv后它不再称为pe,而是成为le。

  • dm(device mapper):将一个或多个底层块设备组织成一个逻 辑设备的模块

2. LVM写入机制

  LV是从VG中划分出来的,LV中的PE很可能来自于多个PV。在向LV存储数据时,有多种存储机制,其中两种是:

  • 线性模式(linear):先写完来自于同一个PV的PE,再写来自于下一个PV的PE。
  • 条带模式(striped):一份数据拆分成多份,分别写入该LV对应的每个PV中,所以读写性能较好,类似于RAID 0。

  尽管striped读写性能较好也不建议使用该模式,因为lvm的着重点在于弹性容量扩展而非性能,要实现性能应该使用RAID来实现,而且使用striped模式时要进行容量的扩展和收缩将比较麻烦。默认的是使用线性模式

3. LVM使用

  在通过磁盘创建LVM时,需要在修改分区本身的分区类别,如果直接使用磁盘,则不需要修改。LVM的分区类型为:8e
  dm: device mapper:将一个或多个底层块设备组织成一个逻 辑设备的模块 设备名:/dev/dm-#

3.1 物理卷(PV)

3.1.1 显示pv信息

用于显示pv信息的命令有:pvs,pvscan,pvdisplay

  • pvs : 显示物理卷的概要信息
[root@localhost ~]# pvs
  PV         VG       Fmt  Attr PSize  PFree
  /dev/sda2  VolGroup lvm2 a--u 19.51g    0
  /dev/sdb1  vg0      lvm2 a--u  5.01g 8.00m
  /dev/sdc1  vg0      lvm2 a--u  5.01g 5.01g
  /dev/sdd1  vg0      lvm2 a--u  5.01g 5.01g
  /dev/sde1  vg0      lvm2 a--u  5.01g 5.01g

  • pvscan : 扫描系统中连接的所有硬盘,列出找到的物理卷列表
    • -n :仅显示不属于任何卷组的物理卷;
    • -u :显示UUID;
    • -b : 后台运行
[root@localhost ~]# pvscan -u
  PV /dev/sdb1 with UUID rvCk7p-MunV-2rbS-Ciwl-5zVX-USHk-0ue8Hi    VG vg0             lvm2 [5.01 GiB / 8.00 MiB free]
  PV /dev/sdc1 with UUID uEZ433-e2ou-QjwG-Faqb-OKPu-09fM-RpKF2e    VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sdd1 with UUID MM6l3C-7Okj-eYSX-PdIu-2Xki-ZnOi-u9wmUj    VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sde1 with UUID BksyNI-HUjB-0hSV-egHG-3GDw-BPkZ-S5Pand    VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sda2 with UUID 0flXKZ-P8ZB-at1K-pmnr-XTIf-LimS-i05Tn6    VG VolGroup        lvm2 [19.51 GiB / 0    free]
  Total: 5 [39.54 GiB] / in use: 5 [39.54 GiB] / in no VG: 0 [0   ]
[root@localhost ~]# pvscan
  PV /dev/sdb1   VG vg0             lvm2 [5.01 GiB / 8.00 MiB free]
  PV /dev/sdc1   VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sdd1   VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sde1   VG vg0             lvm2 [5.01 GiB / 5.01 GiB free]
  PV /dev/sda2   VG VolGroup        lvm2 [19.51 GiB / 0    free]
  Total: 5 [39.54 GiB] / in use: 5 [39.54 GiB] / in no VG: 0 [0   ]

  • pvdisplay :显示的详细物理卷信息包括:物理卷名称所属的卷组物理卷大小PE大小总PE数可用PE数已分配的PE数UUID
    • -m : 显示PE到LE的映射。
[root@localhost ~]# pvdisplay  /dev/sdb1
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               vg0
  PV Size               5.01 GiB / not usable 2.10 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              1282
  Free PE               2
  Allocated PE          1280
  PV UUID               rvCk7p-MunV-2rbS-Ciwl-5zVX-USHk-0ue8Hi
[root@localhost ~]# pvdisplay  /dev/sdb1  -m
  --- Physical volume ---
  PV Name               /dev/sdb1
  VG Name               vg0
  PV Size               5.01 GiB / not usable 2.10 MiB
  Allocatable           yes
  PE Size               4.00 MiB
  Total PE              1282
  Free PE               2
  Allocated PE          1280
  PV UUID               rvCk7p-MunV-2rbS-Ciwl-5zVX-USHk-0ue8Hi

  --- Physical Segments ---
  Physical extent 0 to 1279:
    Logical volume	/dev/vg0/lv0
    Logical extents	0 to 1279
  Physical extent 1280 to 1281:
    FREE

3.1.2 创建PV

使用pvcreate 命令创建pv

  • -f:强制创建物理卷,不需要用户确认;
  • -u:指定设备的UUID;
  • -y:所有的问题都回答“yes”
[root@localhost ~]# pvcreate /dev/sd{b,c,d,e}1
  Physical volume "/dev/sdb1" successfully created
  Physical volume "/dev/sdc1" successfully created
  Physical volume "/dev/sdd1" successfully created
  Physical volume "/dev/sde1" successfully created

3.1.3 删除pv

使用pvremove命令删除对应的pv

  • -f:强制删除;
  • -y:对提问回答“yes”。
[root@localhost ~]# pvremove /dev/sd{b,c,d,e}1
  Labels on physical volume "/dev/sdb1" successfully wiped
  Labels on physical volume "/dev/sdc1" successfully wiped
  Labels on physical volume "/dev/sdd1" successfully wiped
  Labels on physical volume "/dev/sde1" successfully wiped

3.1.4 移动pv中的数据

使用pvmove

  • -n vgname :仅移动vgname对应区域的数据
pvmove -n vgname /dev/sdb1
将sdb1中属于vgname的数据移动到vgname逻辑卷的其他区域

3.1.5 扩展pv

pvresize :扩展本身的空间

[root@localhost ~]# pvcreate /dev/sde
  Physical volume "/dev/sde" successfully created
[root@localhost ~]# pvs /dev/sde
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sde        lvm2 ---- 40.00g 40.00g
之后虚拟机扩展硬盘本身空间到50G
[root@localhost ~]# pvresize /dev/sde
  Physical volume "/dev/sde" changed
  1 physical volume(s) resized / 0 physical volume(s) not resized
[root@localhost ~]# pvs /dev/sde
  PV         VG   Fmt  Attr PSize  PFree
  /dev/sde        lvm2 ---- 50.00g 50.00g

3.1.6 修改pv信息

pvchange:允许管理员改变物理卷的分配许可。如果物理卷出现故障,可以使用pvchange命令禁止分配物理卷上的PE。

  • -u:生成新的UUID;
  • -x:是否允许分配对应磁盘的PE空间。
[root@localhost ~]# pvchange -u /dev/sde
  Physical volume "/dev/sde" changed
  1 physical volume changed / 0 physical volumes not changed
[root@localhost ~]# blkid /dev/sde
/dev/sde: UUID="eLC0Ea-brQU-bDJ6-DylC-c2yL-AcqG-0heGXE" TYPE="LVM2_member"
[root@localhost ~]# pvchange -x n /dev/sde
  Allocatability not supported by orphan lvm2 format PV /dev/sde
  Physical volume /dev/sde not changed
  0 physical volumes changed / 1 physical volume not changed
[root@localhost ~]# pvchange -x y /dev/sde
  Allocatability not supported by orphan lvm2 format PV /dev/sde
  Physical volume /dev/sde not changed
  0 physical volumes changed / 1 physical volume not changed

3.2 卷组(VG)

3.2.1 创建VG

vgcreate:用于创建LVM卷组

  • -l:卷组上允许创建的最大逻辑卷(lv)数;
  • -p:卷组中允许添加的最大物理卷(pv)数;
  • -s:卷组上的物理卷的PE大小。
    示例:
[root@localhost ~]# vgcreate -p 3 -l 1 vg0 /dev/sdb1 /dev/sdc1 /dev/sde  /dev/sdd1
  No space for '/dev/sdd1' - volume group 'vg0' holds max 3 physical volume(s).
  Unable to add physical volume '/dev/sdd1' to volume group 'vg0'.
[root@localhost ~]# vgcreate -p 3 -l 1 vg0 /dev/sdb1 /dev/sdc1 /dev/sde
  Volume group "vg0" successfully created
[root@localhost ~]# lvcreate -L 5G -n lv0 vg0
  Logical volume "lv0" created.
[root@localhost ~]# lvcreate -L 5G -n lv1 vg0
  Maximum number of logical volumes (1) reached in volume group vg0
[root@localhost ~]#

3.2.2 查看vg信息

  • vgs: 显示逻辑卷的概要信息
[root@localhost ~]# vgs
  VG       #PV #LV #SN Attr   VSize  VFree
  VolGroup   1   2   0 wz--n- 19.51g     0
  vg0        3   1   0 wz--n- 60.01g 55.01g

  • vgscan : 查找所有的卷组
[root@localhost ~]# vgscan
  Reading all physical volumes.  This may take a while...
  Found volume group "vg0" using metadata type lvm2
  Found volume group "VolGroup" using metadata type lvm2

  • vgdisplay : 显示卷组详细信息
    • -s : 使用短格式输出的信息。
[root@localhost ~]# vgdisplay vg0
  --- Volume group ---
  VG Name               vg0
  System ID
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  2
  VG Access             read/write
  VG Status             resizable
  MAX LV                1
  Cur LV                1
  Open LV               0
  Max PV                3
  Cur PV                3
  Act PV                3
  VG Size               60.01 GiB
  PE Size               4.00 MiB
  Total PE              15363
  Alloc PE / Size       1280 / 5.00 GiB
  Free  PE / Size       14083 / 55.01 GiB
  VG UUID               QmnfQY-xKbj-7uUV-H0uZ-b4Lu-SA9p-2iPYDm

3.2.3 删除卷组

  • vgremove : 用于用户删除LVM卷组
    • -f: 强制删除
[root@localhost ~]# vgremove vg0
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
Do you really want to remove volume group "vg0" containing 1 logical volumes? [y/n]: y
  Logical volume "lv0" successfully removed
  Volume group "vg0" successfully removed

3.2.4 重命名卷组

  • vgrename : 重命名卷组的名称
[root@localhost ~]# vgrename vg0 vg100
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  Volume group "vg0" successfully renamed to "vg100"

3.2.5 修改卷组的属性

  • vgchange options vgname
  • options
    • -a y|n: 设置卷组活动状态,y:表示激活,n:表示非激活状态
[root@localhost ~]# vgchange -an vg100
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  0 logical volume(s) in volume group "vg100" now active
[root@localhost ~]# vgchange -ay vg100
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  1 logical volume(s) in volume group "vg100" now active

3.2.6 导入导出卷组

  • vgexport :导出卷组
  • vgimport : 导入卷组
[root@localhost ~]# vgchange -a n vg0
  0 logical volume(s) in volume group "vg0" now active

[root@localhost ~]# vgexport vg0
  Volume group "vg0" successfully exported
[root@localhost ~]# vgdisplay  vg0
  --- Volume group ---
  VG Name               vg0
  System ID
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  3
  VG Access             read/write
  VG Status             exported/resizable
  MAX LV                1
  Cur LV                1
  Open LV               0
  Max PV                3
  Cur PV                3
  Act PV                3
  VG Size               60.01 GiB
  PE Size               4.00 MiB
  Total PE              15363
  Alloc PE / Size       1280 / 5.00 GiB
  Free  PE / Size       14083 / 55.01 GiB
  VG UUID               QmnfQY-xKbj-7uUV-H0uZ-b4Lu-SA9p-2iPYDm

[root@localhost ~]# vgimport vg0
  Volume group "vg0" successfully imported
[root@localhost ~]# vgdisplay  vg0
  --- Volume group ---
  VG Name               vg0
  System ID
  Format                lvm2
  Metadata Areas        3
  Metadata Sequence No  4
  VG Access             read/write
  VG Status             resizable
  MAX LV                1
  Cur LV                1
  Open LV               0
  Max PV                3
  Cur PV                3
  Act PV                3
  VG Size               60.01 GiB
  PE Size               4.00 MiB
  Total PE              15363
  Alloc PE / Size       1280 / 5.00 GiB
  Free  PE / Size       14083 / 55.01 GiB
  VG UUID               QmnfQY-xKbj-7uUV-H0uZ-b4Lu-SA9p-2iPYDm


3.2.7 更改卷组容量

  • vgextend : 用于动态扩展LVM卷组,它通过向卷组中添加物理卷(pv)来增加卷组的容量

  • vgreduce:通过删除LVM卷组中的物理卷(pv)来减少卷组容量

[root@localhost ~]# vgextend vg100 /dev/sde
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  Volume group "vg100" successfully extended
[root@localhost ~]# vgreduce vg100 /dev/sde
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  Removed "/dev/sde" from volume group "vg100"
[root@localhost ~]# vgreduce vg100 /dev/sdb1
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  Physical volume "/dev/sdb1" still in use

3.3 逻辑卷(lv)

3.3.1 查看逻辑卷信息

  • lvs : 查看逻辑卷大致信息
[root@localhost ~]# lvs
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  LV      VG       Attr       LSize  Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  lv_root VolGroup -wi-ao---- 17.51g
  lv_swap VolGroup -wi-ao----  2.00g
  lv100   vg100    -wi-a-----  5.00g
  • lvscan : 扫描系统中的所有逻辑卷
[root@localhost ~]# lvscan
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  ACTIVE            '/dev/vg100/lv100' [5.00 GiB] inherit
  ACTIVE            '/dev/VolGroup/lv_root' [17.51 GiB] inherit
  ACTIVE            '/dev/VolGroup/lv_swap' [2.00 GiB] inherit

  • lvdisplay : 用于显示LVM逻辑卷空间大小、读写状态和快照信息等属性。
[root@localhost ~]# lvdisplay   /dev/vg100/lv100
  WARNING: Locking disabled. Be careful! This could corrupt your metadata.
  --- Logical volume ---
  LV Path                /dev/vg100/lv100
  LV Name                lv100
  VG Name                vg100
  LV UUID                9YzC3b-rAJs-Lh8u-cogN-3fdK-P8ii-bvwCPc
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-10-06 00:15:26 +0800
  LV Status              available
  # open                 0
  LV Size                5.00 GiB
  Current LE             1280
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:2

取消其中警报的方式:编辑/etc/lvm/lvm.conf中开启lock,locking_type = 1

3.3.2 创建逻辑卷

lvcreate : 用于创建LVM的逻辑卷。

  • -L:指定逻辑卷的大小,单位为“kKmMgGtT”字节;
  • -l:指定逻辑卷的大小(LE|PE数)。(%{VG|FREE})
  • -s : 创建的逻辑卷为快照
  • -p,–permission [r|rw] :手动设置权限属性
[root@localhost ~]# lvcreate -n lv1 -l 100 vg100
  Logical volume "lv1" created.
#一般PE大小为4M 所以通过上面那个命令创建出来的逻辑卷是400M
[root@localhost ~]# lvcreate -n lv2 -l 60%VG  vg100
  Logical volume "lv2" created.
#占用VG%60空间创建逻辑卷
[root@localhost ~]# lvdisplay /dev/vg100/lv2
  --- Logical volume ---
  LV Path                /dev/vg100/lv2
  LV Name                lv2
  VG Name                vg100
  LV UUID                hRGa2T-OuIl-RH1s-5OYq-h31J-Z2Fk-MTtMBs
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-10-06 01:21:36 +0800
  LV Status              available
  # open                 0
  LV Size                39.01 GiB
  Current LE             9987
  Segments               1
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:4

[root@localhost ~]# lvcreate -n lv3 -l 60%FREE  vg100
  Logical volume "lv3" created.
#使用剩余可用空间的60%创建逻辑卷
[root@localhost ~]# lvdisplay /dev/vg100/lv3
  --- Logical volume ---
  LV Path                /dev/vg100/lv3
  LV Name                lv3
  VG Name                vg100
  LV UUID                4M70ie-eMOo-7pdr-r81f-yNLi-Bfv4-urNrIJ
  LV Write Access        read/write
  LV Creation host, time localhost.localdomain, 2018-10-06 01:22:46 +0800
  LV Status              available
  # open                 0
  LV Size                12.37 GiB
  Current LE             3166
  Segments               2
  Allocation             inherit
  Read ahead sectors     auto
  - currently set to     256
  Block device           253:5


3.3.3 删除逻辑卷

lvremove : 用于删除指定LVM逻辑卷。

[root@localhost ~]# lvremove /dev/vg100/lv3
Do you really want to remove active logical volume lv3? [y/n]: y
  Logical volume "lv3" successfully removed

3.3.4 扩展逻辑卷空间大小

lvextend: 用于在线扩展逻辑卷的空间大小,而不中断应用程序对逻辑卷的访问。

  • -L [+]#[mMgGtT] :指定逻辑卷的大小,单位为“kKmMgGtT”字节;
  • -l:指定逻辑卷的大小(LE|PE数)。(%{VG|FREE})
  • -r : 直接修改文件系统大小
[root@localhost ~]# lvextend -L +4G /dev/vg100/lv100
  Size of logical volume vg100/lv100 changed from 9.00 GiB (2304 extents) to 13.00 GiB (3328 extents).
  Logical volume lv100 successfully resized.
[root@localhost ~]# resize2fs  /dev/vg100/lv100
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/vg100/lv100 is mounted on /mnt; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 1
Performing an on-line resize of /dev/vg100/lv100 to 3407872 (4k) blocks.
The filesystem on /dev/vg100/lv100 is now 3407872 blocks long.
如果直接在lvextend之后 -r ,可以直接扩展文件系统大小。
[root@localhost ~]# lvextend -L +4G -r /dev/vg100/lv100
  Size of logical volume vg100/lv100 changed from 13.00 GiB (3328 extents) to 17.00 GiB (4352 extents).
  Logical volume lv100 successfully resized.
resize2fs 1.41.12 (17-May-2010)
Filesystem at /dev/mapper/vg100-lv100 is mounted on /mnt; on-line resizing required
old desc_blocks = 1, new_desc_blocks = 2
Performing an on-line resize of /dev/mapper/vg100-lv100 to 4456448 (4k) blocks.
The filesystem on /dev/mapper/vg100-lv100 is now 4456448 blocks long.


3.3.5 减少逻辑卷空间

lvreduce : 用于减少LVM逻辑卷占用的空间大小。

  • 具体步骤
    • umount /mnt/lv0
    • fsck -f /dev/vg0/lv0
    • resize2fs /dev/vg0/lv0 8G
    • lvreduce -L 8G /dev/vg0/lv0
[root@localhost ~]# e2fsck -f /dev/vg100/lv0
e2fsck 1.41.12 (17-May-2010)
Pass 1: Checking inodes, blocks, and sizes
Pass 2: Checking directory structure
Pass 3: Checking directory connectivity
Pass 4: Checking reference counts
Pass 5: Checking group summary information
/dev/vg100/lv0: 11/655360 files (0.0% non-contiguous), 76783/2621440 blocks
[root@localhost ~]# lvreduce -L -5G -r /dev/vg100/lv0
fsck from util-linux-ng 2.17.2
/dev/mapper/vg100-lv0: clean, 11/655360 files, 76783/2621440 blocks
resize2fs 1.41.12 (17-May-2010)
Resizing the filesystem on /dev/mapper/vg100-lv0 to 1310720 (4k) blocks.
The filesystem on /dev/mapper/vg100-lv0 is now 1310720 blocks long.

  Size of logical volume vg100/lv0 changed from 10.00 GiB (2560 extents) to 5.00 GiB (1280 extents).
  Logical volume lv0 successfully resized.

3.3.6 给逻辑卷重命名

lvrename :重命令逻辑卷

[root@localhost ~]# lvrename /dev/vg100/lv0 /dev/vg100/lv100
  Renamed "lv0" to "lv100" in volume group "vg100"

4. 移动硬盘至新的主机步骤

  • 源主机中
    1. 在旧系统中,umount所有卷组上的逻辑卷
    2. vgchange –a n vg0 ;lvdisplay
    3. vgexport vg0 ;pvscan ; vgdisplay
  • 目标主机中
    5. 在新系统中安装旧硬盘,并vgimport vg0
    6. vgchange –ay vg0
    7. mount所有卷组上的逻辑卷

5 逻辑卷中的快照功能

  快照是特殊的逻辑卷,它是在生成快照时存在的逻辑卷的准确拷贝。 对于需要备份或者复制现有数据集临时拷贝以及其它操作来说, 快照是最合适的选择。
  快照只有在它们和原来的逻辑卷不同时才会消耗空间 。在生成快照时会分配给它一定的空间,但只有在原来的逻辑卷或 者快照有所改变才会使用这些空间。 当原来的逻辑卷中有所改变时,会将旧的数据复制到快照中。快照中只含有原来的逻辑卷更改的数据或者自生成快照后的快 照中更改的数据。 建立快照的卷大小只需要原始逻辑卷15%~20%就够了,也可 以使用lvextend放大快照
  逻辑卷中的快照可以直接通过lvcreate创建有快照功能的逻辑卷实现这个功能。直接指明逻辑卷需要创建的逻辑卷可以在原有的卷组中创建快照卷信息。创建的快照卷无需创建文件系统即可使用。

[root@localhost /]# lvcreate -L 1G -s -n lv100-snapshot-1 -p r /dev/vg100/lv100
  Logical volume "lv100-snapshot-1" created.
[root@localhost /]# mount /dev/vg100/lv100-snapshot-1  /media/
mount: block device /dev/mapper/vg100-lv100--snapshot--1 is write-protected, mounting read-only
[root@localhost /]# cd /media/
[root@localhost media]# ls
adjtime                cron.hourly              fstab             issue.net       mtab            profile.d       rsyslog.d       sysconfig
aliases                cron.monthly             gai.conf          kdump-adv-conf  my.cnf          protocols       rwtab           sysctl.conf
aliases.db             crontab                  gcrypt            kdump.conf      netconfig       quotagrpadmins  rwtab.d
[root@localhost media]# df -h
Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/VolGroup-lv_root
                       18G  1.2G   16G   8% /
tmpfs                 939M     0  939M   0% /dev/shm
/dev/sda1             477M   40M  412M   9% /boot
/dev/mapper/vg100-lv100
                      4.8G   40M  4.6G   1% /mnt
/dev/mapper/vg100-lv100--snapshot--1
                      4.8G   40M  4.6G   1% /media
[root@localhost /]# lvconvert --merge vg100/lv100-snapshot
  Merging of volume lv100-snapshot started.
  lv100: Merged: 100.0%
  Merge of snapshot into logical volume lv100 has finished.
  Logical volume "lv100-snapshot" successfully removed
#通过lvconvert --merge 命令回复数据, 如果使用这个命令之后快照会自动消失。恢复数据时,需要卸载快照的逻辑卷否则恢复会失败。

6 遇到问题

  1. 设置集群之后,lvm取消集群之后有报警Skipping clustered volume group。需要在配置文件/etc/lvm/lvm.conf关闭lock,locking_type = 0
  2. 缩容时一定要先检查文件系统,之后在减少文件系统大小,否则文件系统的超级块会消失。文件系统会缺失。

10-06 13:00