etclvmlvm.conf移除会有怎样的后果？

不能再访问LVM，无法重启机子

在Linux下面一切都是文件，可以学习lvmconf这个命令，《Linux就该这么学》有命令大全

lvmconf命令 – LVM配置修改

vmconf命令的作用是可以修改在LVM配置文件中锁定的配置。

LVM全拼为Logical Volume Manager ，逻辑卷管理LVM是一个多才多艺的硬盘系统工具，无论在linux或者其他类似的系统，都是非常的好用。

使用LVM的基本步骤如下:

1. 安装lvm2 ( apt-get install lvm2 )

2. 使用fdisk分区指定的物理硬盘

3. 使用lvm管理工具进行lvm配置 (建立PV / VG / LV)

4. 格式化已经设置好的LV逻辑卷.挂载到指定目录.

5. 关于如何增加/删除/修改LV逻辑卷大小.请期待第2季.

4. LVM 配置步骤:

# 查看物理磁盘状态 - 硬盘(容量1GB) /dev/sdb 已经识别

Debian:/home/reistlin# fdisk -l

Disk /dev/sda: 10.7 GB, 10737418240 bytes

255 heads, 63 sectors/track, 1305 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Disk identifier: 0x0002db3a

Device Boot Start End Blocks Id System

/dev/sda1 1 1033 8297541 83 Linux

/dev/sda2 1034 1305 2184840 82 Linux swap / Solaris

Disk /dev/sdb: 1073 MB, 1073741824 bytes

128 heads, 32 sectors/track, 512 cylinders

Units = cylinders of 4096 * 512 = 2097152 bytes

Disk identifier: 0x00000000

Disk /dev/sdb doesn't contain a valid partition table

# 使用 fdisk 对 /dev/sdb 分区

Debian:/home/reistlin# fdisk /dev/sdb

Device contains neither a valid DOS partition table, nor Sun, SGI or OSF disklabel

Building a new DOS disklabel with disk identifier 0x4e896764.

Changes will remain in memory only, until you decide to write them.

After that, of course, the previous content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Command (m for help): new

Command action

e extended

p primary partition (1-4)

p

Partition number (1-4): 1

First cylinder (1-512, default 1):

Using default value 1

Last cylinder or +size or +sizeM or +sizeK (1-512, default 512):

Using default value 512

Command (m for help): m

Command action

a toggle a bootable flag

b edit bsd disklabel

c toggle the dos compatibility flag

d delete a partition

l list known partition types

m print this menu

n add a new partition

o create a new empty DOS partition table

p print the partition table

q quit without saving changes

s create a new empty Sun disklabel

t change a partition's system id

u change display/entry units

v verify the partition table

w write table to disk and exit

x extra functionality (experts only)

Command (m for help): w

The partition table has been altered!

Calling ioctl() to re-read partition table.

Syncing disks.

# 查看分区后的物理磁盘信息 - /dev/sdb1 状态正常

Debian:/home/reistlin# fdisk -l

Disk /dev/sda: 10.7 GB, 10737418240 bytes

255 heads, 63 sectors/track, 1305 cylinders

Units = cylinders of 16065 * 512 = 8225280 bytes

Disk identifier: 0x0002db3a

Device Boot Start End Blocks Id System

/dev/sda1 1 1033 8297541 83 Linux

/dev/sda2 1034 1305 2184840 82 Linux swap / Solaris

Disk /dev/sdb: 1073 MB, 1073741824 bytes

128 heads, 32 sectors/track, 512 cylinders

Units = cylinders of 4096 * 512 = 2097152 bytes

Disk identifier: 0x4e896764

Device Boot Start End Blocks Id System

/dev/sdb1 1 512 1048560 83 Linux

# 进入 LVM 模式

Debian:/home/reistlin# lvm

# 查看 LVM 磁盘状态 - 目前没有任何 LVM 磁盘信息

lvm>lvmdiskscan

/dev/ram0 [ 8.00 MB]

/dev/ram1 [ 8.00 MB]

/dev/root [ 7.91 GB]

/dev/ram2 [ 8.00 MB]

/dev/sda2 [ 2.08 GB]

/dev/ram3 [ 8.00 MB]

/dev/ram4 [ 8.00 MB]

/dev/ram5 [ 8.00 MB]

/dev/ram6 [ 8.00 MB]

/dev/ram7 [ 8.00 MB]

/dev/ram8 [ 8.00 MB]

/dev/ram9 [ 8.00 MB]

/dev/ram10 [ 8.00 MB]

/dev/ram11 [ 8.00 MB]

/dev/ram12 [ 8.00 MB]

/dev/ram13 [ 8.00 MB]

/dev/ram14 [ 8.00 MB]

/dev/ram15 [ 8.00 MB]

/dev/sdb [ 1.00 GB]

2 disks

17 partitions

0 LVM physical volume whole disks

0 LVM physical volumes

# 查看 LVM 配置文件 - dump 模式

lvm>dumpconfig

devices {

dir="/dev"

scan="/dev"

preferred_names=[]

filter="a/.*/"

cache_dir="/etc/lvm/cache"

cache_file_prefix=""

write_cache_state=1

sysfs_scan=1

md_component_detection=1

ignore_suspended_devices=0

}

activation {

missing_stripe_filler="/dev/ioerror"

reserved_stack=256

reserved_memory=8192

process_priority=-18

mirror_region_size=512

readahead="auto"

mirror_log_fault_policy="allocate"

mirror_device_fault_policy="remove"

}

global {

umask=63

test=0

units="h"

activation=1

proc="/proc"

locking_type=1

fallback_to_clustered_locking=1

fallback_to_local_locking=1

locking_dir="ar/lock/lvm"

}

shell {

history_size=100

}

backup {

backup=1

backup_dir="/etc/lvm/backup"

archive=1

archive_dir="/etc/lvm/archive"

retain_min=10

retain_days=30

}

log {

verbose=0

syslog=1

overwrite=0

level=0

indent=1

command_names=0

prefix=" "

}

# 创建 Physical Volume (PV)

lvm>pvcreate

Please enter a physical volume path

lvm>pvcreate /dev/sdb1

Physical volume "/dev/sdb1" successfully created

# 查看 Physical Volume (PV) 状态

lvm>pvdisplay

CTRL-c detected: giving up waiting for lock

--- Physical volume ---

PV Name /dev/sdb1

VG Name vg_test

PV Size 1023.98 MB / not usable 3.98 MB

Allocatable yes (but full)

PE Size (KByte) 4096

Total PE 255

Free PE 0

Allocated PE 255

PV UUID SwfyW5-veGN-1Ptd-VIUo-0I3I-CdVB-QF7BwC

# 再次查看 LVM 磁盘状态

lvm>lvmdiskscan

/dev/ram0 [ 8.00 MB]

/dev/ram1 [ 8.00 MB]

/dev/root [ 7.91 GB]

/dev/ram2 [ 8.00 MB]

/dev/sda2 [ 2.08 GB]

/dev/ram3 [ 8.00 MB]

/dev/ram4 [ 8.00 MB]

/dev/ram5 [ 8.00 MB]

/dev/ram6 [ 8.00 MB]

/dev/ram7 [ 8.00 MB]

/dev/ram8 [ 8.00 MB]

/dev/ram9 [ 8.00 MB]

/dev/ram10 [ 8.00 MB]

/dev/ram11 [ 8.00 MB]

/dev/ram12 [ 8.00 MB]

/dev/ram13 [ 8.00 MB]

/dev/ram14 [ 8.00 MB]

/dev/ram15 [ 8.00 MB]

/dev/sdb1 [ 1023.98 MB] LVM physical volume

1 disk

17 partitions

0 LVM physical volume whole disks

1 LVM physical volume

# 创建 Volume Group (VG)

lvm>vgcreate vg_test

Please enter physical volume name(s)

lvm>vgcreate vg_test /dev/sdb1

Volume group "vg_test" successfully created

# 查看 Volume Group (VG) 状态

lvm>vgdisplay

--- Volume group ---

VG Name vg_test

System ID

Format lvm2

Metadata Areas 1

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 1

Act PV 1

VG Size 1020.00 MB

PE Size 4.00 MB

Total PE 255

Alloc PE / Size 0 / 0

Free PE / Size 255 / 1020.00 MB

VG UUID Dbm7gQ-HDao-0z2Z-2u3q-XK9A-bmEv-ES3qC0

# 创建 Logical Volume (LV) 如果需要使用全部VG空间. 输入 -l <Total PE>的值.

# <Total PE>的值可以使用 vgdisplay 命令查看 (Total PE = 255)

lvm>lvcreate -l 255 vg_test -n lv_test

Logical volume "lv_test" created

# 查看 Logical Volume (LV) 状态

lvm>lvdisplay

--- Logical volume ---

LV Name /devg_test/lv_test

VG Name vg_test

LV UUID l3GUct-M3nG-m837-wOe2-4EWo-ZPU6-xskaq8

LV Write Access read/write

LV Status available

# open 0

LV Size 1020.00 MB

Current LE 255

Segments 1

Allocation inherit

Read ahead sectors auto

- currently set to 256

Block device 254:0

# 输入 exit 退出 LVM 配置模式. Ext3 格式化 lv_test 逻辑卷

Debian:/home/reistlin# mkfs -t ext3 -j /devg_test/lv_test

mke2fs 1.41.3 (12-Oct-2008)

Filesystem label=

OS type: Linux

Block size=4096 (log=2)

Fragment size=4096 (log=2)

65280 inodes, 261120 blocks

13056 blocks (5.00%) reserved for the super user

First data block=0

Maximum filesystem blocks=268435456

8 block groups

32768 blocks per group, 32768 fragments per group

8160 inodes per group

Superblock backups stored on blocks:

32768, 98304, 163840, 229376

Writing inode tables: done

Creating journal (4096 blocks): done

Writing superblocks and filesystem accounting information: done

This filesystem will be automatically checked every 25 mounts or

180 days, whichever comes first. Use tune2fs -c or -i to override.

# 挂载 lv_test 逻辑卷到 /mnt 目录. 你也可以挂载到 /home 目录

Debian:/home/reistlin# mount /devg_test/lv_test /mnt

Debian:/home/reistlin# cd /mnt

# 测试文件读写. Reistlin.Com. OKay.

Debian:/mnt# vim Reistlin.Com

Welcome to Reistlin.Com

Debian:/mnt# cat Reistlin.Com

Welcome to Reistlin.Com

最简单的，两台服务器配置成一样，备机关掉，网线拔下（为保险，断开存储连接），切换的时候，关掉主机，启动备机就是了

为了提高切换速度，可以两台都运行，IP不同；共享卷组加tag（配置好lvm.conf，增加volume_list选项），防止同时访问。切换的时候关主机，备机改IP，将共享卷组tag删除，改为自己能激活的tag，然后激活卷组，挂载文件系统，启动应用。相关命令：

vgchange -an sharevg

vgchange --deltag host1 /dev/sharevg

vgchange --addtag host2 /dev/sharevg

vgchange -ay sharevg

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