LVM創建實例及相關注釋

LVM創建 pv—>vg—->lv—->快照

創建前准備了四塊1g硬盤分別為：sdb sdc sdd sde，並分別給四塊盤劃分了1G的空間，並指定了分區系統類型為8e（即Linux LVM）

[root@localhost ~]# fdisk /dev/sdb

Command (m for help): n

Command action

e extended

p primary partition (1-4)

p

Partition number (1-4): 1

First cylinder (1-130, default 1):

Using default value 1

Last cylinder, +cylinders or +size{K,M,G} (1-130, default 130): +999M

Command (m for help): t ##指定類型

Selected partition 1

Hex code (type L to list codes): 8e

Changed system type of partition 1 to 8e (Linux LVM)

Command (m for help): w 保存退出

The partition table has been altered!

然後依次對sdc sdd sde做一樣的操作

[root@localhost ~]# fdisk -l|grep "^/dev/sd"

/dev/sda1 * 1 39 307200 83 Linux

/dev/sda2 39 2358 18631680 83 Linux

/dev/sda3 2358 2611 2031616 82 Linux swap / Solaris

/dev/sdb1 1 128 1028128+ 8e Linux LVM

/dev/sdc1 1 128 1028128+ 8e Linux LVM

/dev/sdd1 1 128 1028128+ 8e Linux LVM

/dev/sde1 1 128 1028128+ 8e Linux LVM

以上紅色顯示的是即將用於創建lvm的分區

First 創建pv

[root@localhost ~]# pvcreate /dev/sd{b,c,d,e}1 創建 PV

Physical volume "/dev/sdb1" successfully created

Physical volume "/dev/sdc1" successfully created

Physical volume "/dev/sdd1" successfully created

Physical volume "/dev/sde1" successfully created

[root@localhost ~]# pvs 查看pv

PV VG Fmt Attr PSize PFree

/dev/sdb1 lvm2 a– 1004.03m 1004.03m

/dev/sdc1 lvm2 a– 1004.03m 1004.03m

/dev/sdd1 lvm2 a– 1004.03m 1004.03m

/dev/sde1 lvm2 a– 1004.03m 1004.03m

[root@localhost ~]# pvdisplay 相對pvs來說顯示的更詳細，以下是/dev/sdb1的顯示內容

"/dev/sdb1" is a new physical volume of "1004.03 MiB"

— NEW Physical volume —

PV Name /dev/sdb1

VG Name

PV Size 1004.03 MiB

Allocatable NO

PE Size 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID 8etjmo-mVi0-ncst-Em9d-pMW0-z0Ol-q4fX8v

pvremove /dev/sdb1 即可刪除

pvcreate /dev/sdb1 則可再加進來

Second 創建pv後創建vg

[root@localhost ~]# vgcreate myvg /dev/sd{b,c,d}1 這裡我們先加進來3塊盤，另一塊用於演示其他操作

Volume group "myvg" successfully created

如果要修改PE大小：可以使用-s參數 默認是4m

查看

[root@localhost ~]# vgs

VG #PV #LV #SN Attr VSize VFree

myvg 3 0 0 wz–n- 2.93g 2.93g

[root@localhost ~]# vgdisplay 同樣也比vgs顯示的詳細

— Volume group —

VG Name myvg

System ID

Format lvm2

Metadata Areas 3

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 3

Act PV 3

VG Size 2.93 GiB

PE Size 4.00 MiB

Total PE 750

Alloc PE / Size 0 / 0

Free PE / Size 750 / 2.93 GiB

VG UUID hbiddu-b9z4-WTxe-CwYK-WrNu-J0Af-tgLWZR

[root@localhost ~]# vgextend myvg /dev/sde1 添加硬盤到vg 增加磁盤沒什麼風險

Volume group "myvg" successfully extended

[root@localhost ~]# vgs 剛才是3個pv 現在4個且容量也增加了

VG #PV #LV #SN Attr VSize VFree

myvg 4 0 0 wz–n- 3.91g 3.91g

下面是移除磁盤，這是我沒要考慮是否磁盤上有數據，如果有移到其他pv，然後移除

[root@localhost ~]# pvmove /dev/sdb1 ##移走數據

No data to move for myvg

[root@localhost ~]# vgreduce myvg /dev/sdb1 ##mypv移除/dev/sdb1

Removed "/dev/sdb1" from volume group "myvg"

[root@localhost ~]# vgs

VG #PV #LV #SN Attr VSize VFree

myvg 3 0 0 wz–n- 2.93g 2.93g

Third 創建邏輯卷lv，及擴展大小

[root@localhost ~]# vgs

VG #PV #LV #SN Attr VSize VFree

myvg 4 0 0 wz–n- 3.91g 3.91g

我們查看一共有不到4G的空間，創建的lv大小不能超過上面vg的大小

[root@localhost ~]# lvcreate -L 2G -n mylv myvg ##在myvg上創建一個mylv的邏輯卷大小2G

Logical volume "mylv" created[root@localhost ~]# lvs #查看

LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert

mylv myvg -wi-a—– 2.00g

[root@localhost ~]# lvdisplay 查看

— Logical volume —

LV Path /dev/myvg/mylv

LV Name mylv

VG Name myvg

LV UUID PPPW3e-xAiz-CMNM-RV2o-i8H1-yfIB-9g4KG2

LV Write Access read/write

LV Creation host, time localhost.localdomain, 2015-06-06 21:24:36 -0700

LV Status available

# open 0

LV Size 2.00 GiB

Current LE 512

Segments 3

Allocation inherit

Read ahead sectors auto

– currently set to 256

Block device 253:0

lv的訪問路徑：(此兩者均為符號鏈接，指向的文件為/dev/dm-#)

1./dev/VG_name/LV_name

/dev/myvg/mylv

2./dev/mapper/VG_name-LV_name

/dev/mapper/myvg-mylv

[root@localhost ~]# ll /dev/dm-*

brw-rw—- 1 root disk 253, 0 Jun 6 21:24 /dev/dm-0

[root@localhost ~]# ll /dev/myvg/

lrwxrwxrwx 1 root root 7 Jun 6 21:24 mylv -> ../dm-0

[root@localhost ~]# ll /dev/mapper

lrwxrwxrwx 1 root root 7 Jun 6 21:24 myvg-mylv -> ../dm-0

lv創建好就是一個文件系統，我們就可以使用它了

[root@localhost ~]# mke2fs -t ext4 /dev/myvg/mylv

mke2fs 1.41.12 (17-May-2010)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

Stride=0 blocks, Stripe width=0 blocks

131072 inodes, 524288 blocks

26214 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=536870912

16 block groups

32768 blocks per group, 32768 fragments per group

8192 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376, 294912

Writing inode tables: done

Creating journal (16384 blocks): done

Writing superblocks and filesystem accounting information: done

格式化後創建目錄掛載吧：

[root@localhost ~]# mkdir /mnt/mylv

[root@localhost ~]# mount /dev/myvg/mylv /mnt/mylv

[root@localhost ~]# mount

/dev/sda2 on / type ext4 (rw)

proc on /proc type proc (rw)

sysfs on /sys type sysfs (rw)

devpts on /dev/pts type devpts (rw,gid=5,mode=620)

tmpfs on /dev/shm type tmpfs (rw)

/dev/sda1 on /boot type ext4 (rw)

none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw)

vmware-vmblock on /var/run/vmblock-fuse type fuse.vmware-vmblock (rw,nosuid,nodev,default_permissions,allow_other)

/dev/mapper/myvg-mylv on /mnt/mylv type ext4 (rw)

如果想要長期使用，命令掛載只是暫時的，還要添加到/etc/fstab文件中最後一行增加：

/dev/myvg/mylv /mnt/mylv ext4 defaults 0 0

pv總空間為3.91G，現在只劃給mylv 2G空間，如果不夠用可以擴展mylv

1. lvextend 擴展物理邊界

[root@localhost ~]# lvextend -L 3G /dev/myvg/mylv ###這裡表示擴展到3G

Extending logical volume mylv to 3.00 GiB

Logical volume mylv successfully resized

[root@localhost ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/sda2 18G 2.9G 14G 18% /

tmpfs 495M 0 495M 0% /dev/shm

/dev/sda1 291M 34M 242M 13% /boot

/dev/mapper/myvg-mylv 2.0G 67M 1.9G 4% /mnt/mylv

2.resizefs 擴展邏輯邊界

[root@localhost ~]# resize2fs /dev/myvg/mylv ###這裡表示擴展至物理邊界大小

resize2fs 1.41.12 (17-May-2010)

Filesystem at /dev/myvg/mylv is mounted on /mnt/mylv; on-line resizing required

old desc_blocks = 1, new_desc_blocks = 1

Performing an on-line resize of /dev/myvg/mylv to 786432 (4k) blocks.

The filesystem on /dev/myvg/mylv is now 786432 blocks long.

[root@localhost ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/sda2 18G 2.9G 14G 18% /

tmpfs 495M 0 495M 0% /dev/shm

/dev/sda1 291M 34M 242M 13% /boot

/dev/mapper/myvg-mylv 3.0G 67M 2.8G 3% /mnt/mylv

縮減很危險！！！！！

縮減要離線，首先卸載 umount /mnt/mylv

1.先確定縮減的目錄數據有多少，並確定對應的目標邏輯卷大小中有足夠的空間可容納原來的所有數據

[root@localhost ~]# du -sh /mnt/mylv

20K /mnt/mylv

2.先減少文件系統，並要執行強制檢測

e2fsck -f

[root@localhost ~]# e2fsck -f /dev/myvg/mylv

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/myvg/mylv: 11/196608 files (0.0% non-contiguous), 29500/786432 blocks

3.縮減邊界

resize2fs device

[root@localhost ~]# resize2fs /dev/myvg/mylv 1G

resize2fs 1.41.12 (17-May-2010)

Resizing the filesystem on /dev/myvg/mylv to 262144 (4k) blocks.

The filesystem on /dev/myvg/mylv is now 262144 blocks long.

4.縮減物理邊界

lvreduce -L 1G /dev/myvg/mylv

[root@localhost ~]# lvreduce -L 1G /dev/myvg/mylv

WARNING: Reducing active logical volume to 1.00 GiB

THIS MAY DESTROY YOUR DATA (filesystem etc.)

Do you really want to reduce mylv? [y/n]: y

Reducing logical volume mylv to 1.00 GiB

Logical volume mylv successfully resized

[root@localhost ~]# mount /dev/myvg/mylv /mnt/mylv

[root@localhost ~]# df -h

Filesystem Size Used Avail Use% Mounted on

/dev/sda2 18G 2.9G 14G 18% /

tmpfs 495M 0 495M 0% /dev/shm

/dev/sda1 291M 34M 242M 13% /boot

/dev/mapper/myvg-mylv 1008M 67M 891M 7% /mnt/mylv

快照卷：只能讀，不能寫

注意：快照卷是對某邏輯卷

[root@localhost ~]# mount -o remount,ro /dev/myvg/mylv /mnt/mylv ##先改成只讀

[root@localhost ~]# lvcreate -L 1G -n mylv-snap -p r -s /dev/myvg/mylv ##對mylv做快照為mylv-snap 大小為1G

[root@localhost ~]# mount -o remount,rw /dev/myvg/mylv /mnt/mylv #快照完，立刻改為讀寫或者一個命令行直接執行者三個命令，或者寫腳本

Logical volume "mylv-snap" created

[root@localhost ~]# mount /dev/myvg/mylv-snap /mnt/snap/ 掛載快照

mount: block device /dev/mapper/myvg-mylv–snap is write-protected, mounting read-only

如果不想用了，要刪除怎麼辦？？

umount /mnt/snap

lvremove /dev/myvg/mylv-snap

另外還有：pvremove vgremove等刪除命令，可以用man 查看