lvm的设置

lvm的设置

原理:

LVM:logical volume manager(逻辑卷管理)

LVM可以随意拉伸和缩小，SCSI的硬盘最多只能够分15个区，如果需要更多的分区，怎么办呢，如果分区在规划的时候分小了或者大了，怎么办呢，而LVM很好的就解决了这些问题。

下面开始进行LVM逻辑卷创建的讨论

从上面这个图可以看到，创建逻辑卷的步骤：

Linux分区----------物理卷-----------卷组-----------逻辑卷

1,首先:新建两个分区512M,类型为lvm的分区

[root@station20 ~]# fdisk /dev/sda

Command (m for help): n ##新建分区

First cylinder (1320-2610, default 1320):

Using default value 1320

Last cylinder or +size or +sizeM or +sizeK (1320-2610, default 2610): +512M #分区大小512M

Command (m for help): n

First cylinder (1383-2610, default 1383):

Using default value 1383

Last cylinder or +size or +sizeM or +sizeK (1383-2610, default 2610): +512M

Command (m for help): t ##更改分区类型

Partition number (1-9): 8

Hex code (type L to list codes): 8e ##8e的类型为LVM具体类型可输入L查询

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

Command (m for help): t

Partition number (1-9): 9

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

Changed system type of partition 9 to 8e (Linux LVM)

Command (m for help): w ##保存并退出

The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 16: Device or resource busy.

The kernel still uses the old table.

The new table will be used at the next reboot.

Syncing disks.

[root@station20 ~]# partprobe /dev/sda #使分区立即分区而不需重启

2,创建物理卷

[root@station20 ~]# pvcreate /dev/sda[89]

Wiping software RAID md superblock on /dev/sda8

Physical volume "/dev/sda8" successfully created

Wiping software RAID md superblock on /dev/sda9

Physical volume "/dev/sda9" successfully created

-------------àpvdisplay命令可以查看物理卷的详细信息

[root@station20 ~]# pvdisplay

"/dev/sda9" is a new physical volume of "494.16 MB"

--- NEW Physical volume ---

PV Name /dev/sda9

VG Name

PV Size 494.16 MB

Allocatable NO

PE Size (KByte) 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID BWWolQ-A0Pz-gGD7-zbqu-qoWS-fXyw-uiIETV

"/dev/sda8" is a new physical volume of "494.16 MB"

--- NEW Physical volume ---

PV Name /dev/sda8

VG Name

PV Size 494.16 MB

Allocatable NO

PE Size (KByte) 0

Total PE 0

Free PE 0

Allocated PE 0

PV UUID EewF0N-7X1z-SRnI-WW7A-WrlR-V0aY-fIi9CB

3.创建卷组

[root@station20 ~]# vgcreate vg02 /dev/sda[89]

Volume group "vg02" successfully created

-----------------可以使用vgdisplay查看卷组详细信息

[root@station20 ~]# vgdisplay

--- Volume group ---

VG Name vg02

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 984.00 MB

PE Size 4.00 MB

Total PE 246

Alloc PE / Size 0 / 0

Free PE / Size 246 / 984.00 MB

VG UUID tDd40t-fDoU-ocJo-dFyt-4A4a-xrbr-l7kE6S

4,创建卷

[root@station20 ~]# lvcreate -L 700M -n lv02 vg02 (参数L指定大小,n指定名字)

Logical volume "lv02" created

-------------同样也可使用lvdisplay命令查看lvm详细信息

[root@station20 ~]# lvdisplay /dev/vg02/lv02

--- Logical volume ---

LV Name /dev/vg02/lv02

VG Name vg02

LV UUID zrNmph-jt9m-oQK0-NPoM-D23y-kZG4-Qx8vL2

LV Write Access read/write

LV Status available

# open 0

LV Size 700.00 MB

Current LE 175

Segments 2

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 253:1

---------格式化lvm分区并挂载在/lvm中使用且每次开机都生效.

[root@station20 ~]# mkfs.ext3 /dev/vg02/lv02

[root@station20 ~]# mkdir /lvm

[root@station20 ~]# vim /etc/fstab

/dev/vg02/lv02 /lvm ext3 defaults 0 0

[root@station20 ~]# mount –a

[root@station20 ~]# df –h |grep lv

/dev/mapper/vg02-lv02

689M 17M 638M 3% /lvm

二lvm拉伸与收缩

1,拉伸操作可以在线完成.

-----------拉伸lvm

[root@station20 ~]# lvextend -L 800M /dev/vg02/lv02

Extending logical volume lv02 to 800.00 MB

Logical volume lv02 successfully resized

-----------à拉伸文件系统

[root@statin20 ~]# resize2fs /dev/vg02/lv02

resize2fs 1.39 (29-May-2006)

Filesystem at /dev/vg02/lv02 is mounted on /lvm; on-line resizing required

Performing an on-line resize of /dev/vg02/lv02 to 204800 (4k) blocks.

The filesystem on /dev/vg02/lv02 is now 204800 blocks long.

----------df查看效果

[root@station20 ~]# df -h |grep lv

/dev/mapper/vg02-lv02

788M 17M 734M 3% /lvm

2收缩lvm需要离线操作,而且要严格按照步骤完成,不然影响远大.

--------------首先卸载分区

[root@station20 ~]# umount /lvm/

-------------扫描分区

[root@station20 ~]# e2fsck -f /dev/vg02/lv02

e2fsck 1.39 (29-May-2006)

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/vg02/lv02: 11/104608 files (9.1% non-contiguous), 7571/204800 blocks

---------------à收缩文件系统

[root@station2 ~]# resize2fs /dev/vg02/lv02 500M

resize2fs 1.39 (29-May-2006)

Resizing the filesystem on /dev/vg02/lv02 to 128000 (4k) blocks.

The filesystem on /dev/vg02/lv02 is now 128000 blocks long.

---------------收缩lvm分区

[root@station20 ~]# lvreduce -L 500M /dev/vg02/lv02

WARNING: Reducing active logical volume to 500.00 MB

THIS MAY DESTROY YOUR DATA (filesystem etc.)

Do you really want to reduce lv02? [y/n]: y

Reducing logical volume lv02 to 500.00 MB

Logical volume lv02 successfully resized

-------------重新挂载并查看效果

[root@station20 ~]# mount -a

[root@station20 ~]# df -h |grep lv

/dev/mapper/vg02-lv02

493M 17M 457M 4% /lvm

最后最好重启测试.

简述一下其他命令

--------------添加一个pv进卷组

[root@station20 ~]# vgextend vg02 /dev/sda9

--------------从卷组中移除pv

[root@station20 ~]#vgreduce vg02 /dev/sda9

具体命令请参照-------------man page

三.lvm快照的功能

优点是速度快,快速备份,保持一致性

具体命令

[root@station20 ~]# lvcreate -L 200M -s -n snaplv2 /dev/vg02/lv02

Logical volume "snaplv2" created

这样创建快照完成了,可以只读挂载对分区进行备份,

[root@station20 ~]# mkdir /mnt/snap

[root@station20 ~]# mount -o ro /dev/vg02/snaplv2 /mnt/snap/

备份完之后就可以移除快照了

[root@station20 ~]# umount /mnt/snap/

[root@station20 ~]# lvremove /dev/vg02/snaplv2

Do you really want to remove active logical volume snaplv2? [y/n]: y

Logical volume "snaplv2" successfully removed

LVM基本研究在这里