今天在VMware® Workstation 12 Pro虚拟机上克隆了一台Linux虚拟机，无意中发现两台虚拟机blkid一模一样。
[root@stau64 ~]# blkid
[root@stau65 ~]# blkid
有没有什么办法改变blkid里的UUID呢？网上查找了很多关于如何实现改变UUID的方法，都不怎么好使。最后我实际操作，终于找到一条可以真正改变blkid里UUID的方法，实验步骤如下：
1.准备。为了不与其它系统卷组名称相同从而导致无法被挂载启动。这里我先修改逻辑卷和卷组名称
[root@stau65 ~]# lvrename /dev/centos/root lvroot
[root@stau65 ~]# vgrename centos VolGroup65
2.把系统关机，查看虚拟磁盘文件名称
[root@stau65 ~]# shutdown -h now
2.另起一台虚拟机，添加刚刚查看的虚拟磁盘文件
3.开机，如果无法开机，使用光盘进入rescue修复模式进行修复
[root@stau63 ~]# df -hT
正常启动后如图可以看到我们添加虚拟磁盘，此处显示的/dev/sdb就是需要修改blkid里UUID的磁盘。
[root@stau63 ~]# ll /dev/sd*
4.查看当前所有卷组vgdisplay
[root@stau63 ~]# vgdisplay
--- Volume group ---
VG Name centos
System ID
Format lvm2
Metadata Areas 1
Metadata Sequence No 3
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 2
Max PV 0
Cur PV 1
Act PV 1
VG Size 12.00 GiB
PE Size 4.00 MiB
Total PE 3072
Alloc PE / Size 3072 / 12.00 GiB
Free PE / Size 0 / 0
VG UUID d5xxJl-gMyV-Y1Gj-v57D-fDqY-GvWL-ih6DaL
--- Volume group ---
VG Name VolGroup65
System ID
Format lvm2
Metadata Areas 2
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 2
Open LV 0
Max PV 0
Cur PV 2
Act PV 2
VG Size 21.99 GiB
PE Size 4.00 MiB
Total PE 5630
Alloc PE / Size 5630 / 21.99 GiB
Free PE / Size 0 / 0
VG UUID b4If34-7E1r-rvMN-WpKE-2Kmg-22Ts-auTm1i
查看uuid
[root@stau63 ~]# blkid
5.如果卷组没有激活，需要先激活一下
[root@stau63 ~]# vgchange -ay VolGroup65
-a: activate
-y: yes 激活
-n: no 不激活
6.生成新UUID
6.1XFS系统：
6.1.1改变根分区UUID。
要改变根分区UUID，因为系统采用的是lvm逻辑卷管理，我暂未发现针对lvm类型修改UUID的命令与方法。所以这里我采用备份根分区然后还原的方式。步骤如下：
a.查看卷组剩余空间，发现没有剩余PE
[root@stau63 ~]# vgdisplay VolGroup65
b.查看磁盘空间
[root@stau63 ~]# fdisk -l /dev/sdb
Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xc0412435
Device Boot Start End Blocks Id System
/dev/sdb1 2048 1026047 512000 83 Linux
/dev/sdb2 1026048 5220351 2097152 83 Linux
/dev/sdb3 5220352 47163391 20971520 83 Linux
说明：/dev/sdb1 为引导分区
/dev/sdb2 为swap分区
/dev/sdb3 才是我要备份的根分区
c.因为我怕空间不足，所以这里我把swap分区移除掉。（数据无价，删除任何文件前请确认已经备份好重要数据。删除前需要先取消挂载。）
c.1确认操作的分区没有被挂载
[root@stau63 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/centos-root xfs 10G 7.0G 3.1G 70% /
devtmpfs devtmpfs 224M 0 224M 0% /dev
tmpfs tmpfs 236M 0 236M 0% /dev/shm
tmpfs tmpfs 236M 5.7M 230M 3% /run
tmpfs tmpfs 236M 0 236M 0% /sys/fs/cgroup
/dev/sr0 iso9660 8.8G 8.8G 0 100% /mnt/cdrom
/dev/sda1 xfs 197M 108M 90M 55% /boot
tmpfs tmpfs 48M 0 48M 0% /run/user/0
c.2移除swap分区
[root@stau63 ~]# lvremove /dev/VolGroup65/swap
Do you really want to remove active logical volume VolGroup65/swap? [y/n]: y
Logical volume "swap" successfully removed
[root@stau63 ~]# vgreduce VolGroup65 /dev/sdb2
Removed "/dev/sdb2" from volume group "VolGroup65"
[root@stau63 ~]# pvremove /dev/sdb2
Labels on physical volume "/dev/sdb2" successfully wiped.
d.新建backup-lv,备份根分区
d.1新建磁盘分区。把剩余空间新建一个磁盘分区
[root@stau63 ~]# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.23.2).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): p
Disk /dev/sdb: 42.9 GB, 42949672960 bytes, 83886080 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0xc0412435
Device Boot Start End Blocks Id System
/dev/sdb1 2048 1026047 512000 83 Linux
/dev/sdb2 1026048 5220351 2097152 83 Linux
/dev/sdb3 5220352 47163391 20971520 83 Linux
Command (m for help): n
Partition type:
p primary (3 primary, 0 extended, 1 free)
e extended
Select (default e): e
Selected partition 4
First sector (47163392-83886079, default 47163392):
Using default value 47163392
Last sector, +sectors or +size{K,M,G} (47163392-83886079, default 83886079):
Using default value 83886079
Partition 4 of type Extended and of size 17.5 GiB is set
Command (m for help): n
All primary partitions are in use
Adding logical partition 5
First sector (47165440-83886079, default 47165440):
Using default value 47165440
Last sector, +sectors or +size{K,M,G} (47165440-83886079, default 83886079):
Using default value 83886079
Partition 5 of type Linux and of size 17.5 GiB is set
Command (m for help): w
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 or after you run partprobe(8) or kpartx(8)
Syncing disks.
d.2更新磁盘信息
[root@stau63 ~]# partprobe /dev/sdb
[root@stau63 ~]# ll /dev/sdb*
brw-rw---- 1 root disk 8, 16 Feb 4 17:28 /dev/sdb
brw-rw---- 1 root disk 8, 17 Feb 4 17:28 /dev/sdb1
brw-rw---- 1 root disk 8, 18 Feb 4 17:28 /dev/sdb2
brw-rw---- 1 root disk 8, 19 Feb 4 17:28 /dev/sdb3
brw-rw---- 1 root disk 8, 20 Feb 4 17:28 /dev/sdb4
brw-rw---- 1 root disk 8, 21 Feb 4 17:28 /dev/sdb5
d.3新建pv,扩展vg，并查看vg信息
[root@stau63 ~]# pvcreate /dev/sdb5
Physical volume "/dev/sdb5" successfully created.
[root@stau63 ~]# vgextend VolGroup65 /dev/sdb5
Volume group "VolGroup65" successfully extended
[root@stau63 ~]# vgdisplay VolGroup65
--- Volume group ---
VG Name VolGroup65
System ID
Format lvm2
Metadata Areas 3
Metadata Sequence No 7
VG Access read/write
VG Status resizable
MAX LV 0
Cur LV 1
Open LV 0
Max PV 0
Cur PV 3
Act PV 3
VG Size 39.50 GiB
PE Size 4.00 MiB
Total PE 10112
Alloc PE / Size 5118 / 19.99 GiB
Free PE / Size 4994 / <19.51 GiB
VG UUID b4If34-7E1r-rvMN-WpKE-2Kmg-22Ts-auTm1i
d.4新建备份lv
[root@stau63 ~]# lvcreate -n backup-lv -l +100%Free VolGroup65
Logical volume "backup-lv" created.
d.5格式化lv
[root@stau63 ~]# mkfs.xfs /dev/VolGroup65/backup-lv
meta-data=/dev/VolGroup65/backup-lv isize=512 agcount=4, agsize=1278464 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5113856, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2560, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
d.6挂载
[root@stau63 ~]# mkdir -p /mnt/VolGroup65/lvroot /mnt/VolGroup65/backup-lv
[root@stau63 ~]# mount /dev/mapper/VolGroup65-lvroot /mnt/VolGroup65/lvroot
[root@stau63 ~]# mount /dev/VolGroup65/backup-lv /mnt/VolGroup65/backup-lv
e.备份源lv逻辑卷。此处我使用rsync工具，/boot引导分区因为我需要重建，所以我备份排除此目录下文件。（备份工具有很多，大家可以择优选择。因为我需要改变UUID的值，所以我使用最方便的复制工具rsync.）
[root@stau63 ~]# rsync -avz /mnt/VolGroup65/lvroot /mnt/VolGroup65/backup-lv --exclude=media/* --exclude=sys/* --exclude=proc/* --exclude=mnt/* --exclude=tmp/* --exclude=boot/*
f.移除根分区
[root@stau63 ~]# umount /dev/mapper/VolGroup65-lvroot
[root@stau63 ~]# lvremove /dev/mapper/VolGroup65-lvroot
Do you really want to remove active logical volume VolGroup65/lvroot? [y/n]: y
Logical volume "lvroot" successfully removed
[root@stau63 ~]# vgreduce VolGroup65 /dev/sdb3
Removed "/dev/sdb3" from volume group "VolGroup65"
[root@stau63 ~]# pvremove /dev/sdb3
Labels on physical volume "/dev/sdb3" successfully wiped.
注：如果vgreduce如下失败，需要先pvmove走
[root@stau63 ~]# vgreduce VolGroup65 /dev/sdb3
Physical volume "/dev/sdb3" still in use
可以移动pvmove到另一磁盘，后者Free PE需要大于前者
[root@stau63 ~]# pvmove /dev/sdb3 /dev/sda3
/dev/sdb3: Moved: 0.00%
/dev/sdb3: Moved: 14.65%
/dev/sdb3: Moved: 30.27%
/dev/sdb3: Moved: 75.20%
/dev/sdb3: Moved: 100.00%
到此除了包含备份文件的/dev/sda5，根分区已经备份和移走了，其它分区可以重新分区或者格式化了。
g.重建根分区及还原数据
我选择了重新分区，分区后别忘了partprobe /dev/sdb刷新下分区表
[root@stau63 ~]# partprobe /dev/sda
[root@stau63 ~]# partprobe /dev/sdb
[root@stau63 ~]# ll /dev/sdb*
brw-rw---- 1 root disk 8, 16 Feb 6 16:36 /dev/sdb
brw-rw---- 1 root disk 8, 17 Feb 6 16:36 /dev/sdb1
brw-rw---- 1 root disk 8, 18 Feb 6 16:36 /dev/sdb2
brw-rw---- 1 root disk 8, 19 Feb 6 16:36 /dev/sdb3
brw-rw---- 1 root disk 8, 20 Feb 6 16:36 /dev/sdb4
brw-rw---- 1 root disk 8, 21 Feb 6 16:36 /dev/sdb5
g.1新建PV和新建vg
[root@stau63 ~]# pvcreate /dev/sdb2 /dev/sdb3
Physical volume "/dev/sdb2" successfully created.
Physical volume "/dev/sdb3" successfully created.
[root@stau63 ~]# vgcreate VG65 /dev/sdb{2,3}
Volume group "VG65" successfully created
g.2新建lv
[root@stau63 ~]# lvcreate -L 2G -n swap VG65
Logical volume "swap" created.
[root@stau63 ~]# lvcreate -l 100%Free -n lvroot VG65
Logical volume "lvroot" created.
g.4格式化
引导分区因为必须为标准分区格式，所以直接格式化就好
[root@stau63 ~]# mkfs.xfs /dev/sdb1
meta-data=/dev/sdb1 isize=512 agcount=4, agsize=19200 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=76800, 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
格式化lv
[root@stau63 ~]# mkfs.xfs /dev/mapper/VG65-lvroot
meta-data=/dev/mapper/VG65-lvroot isize=512 agcount=4, agsize=1323008 blks
= sectsz=512 attr=2, projid32bit=1
= crc=1 finobt=0, sparse=0
data = bsize=4096 blocks=5292032, imaxpct=25
= sunit=0 swidth=0 blks
naming =version 2 bsize=4096 ascii-ci=0 ftype=1
log =internal log bsize=4096 blocks=2584, version=2
= sectsz=512 sunit=0 blks, lazy-count=1
realtime =none extsz=4096 blocks=0, rtextents=0
格式化swap分区
[root@stau63 ~]# mkswap /dev/mapper/VG65-swap
Setting up swapspace version 1, size = 2097148 KiB
no label, UUID=2ab4424a-e95d-489a-96f1-c967bc6a7c0c
g.5挂载并还原数据
[root@stau63 ~]# mkdir /mnt/vg65
[root@stau63 ~]# mount /dev/VG65/lvroot /mnt/vg65
[root@stau63 ~]# rsync -avz /mnt/VolGroup65/backup-lv/lvroot/* /mnt/vg65/ --exclude=media/* --exclude=sys/* --exclude=proc/* --exclude=mnt/* --exclude=tmp/* --exclude=boot/*
e.修改/mnt/vg65/etc/fstab
e.1查看新UUID
[root@stau63 vg65]# blkid
/dev/sda1: UUID="a8b7ce70-f1c1-4f73-b13f-d5daf168096f" TYPE="xfs"
/dev/sda2: UUID="kjXpdZ-5Rpy-7tg0-KqiV-9FRg-0OXX-q37J3B" TYPE="LVM2_member"
/dev/sdb1: UUID="ccb49fe1-c127-4e1c-ae0d-996cc17a624e" TYPE="xfs"
/dev/sdb3: UUID="vgZOV0-I24e-xRvb-GIdH-Q5o9-v7Fq-beBFYw" TYPE="LVM2_member"
/dev/sr0: UUID="2018-05-07-12-53-47-00" LABEL="CentOS 7 x86_64" TYPE="iso9660" PTTYPE="dos"
/dev/mapper/centos-root: UUID="7041be13-c88f-4221-b5c2-6d3e55a1c3f2" TYPE="xfs"
/dev/mapper/centos-swap: UUID="0562ef7b-0b3c-4da5-8414-1d13d44dc7f0" TYPE="swap"
/dev/sdb5: UUID="Yfucop-iXE0-vIQh-L0QJ-AUY4-8uAK-FASfAj" TYPE="LVM2_member"
/dev/mapper/VolGroup65-backup--lv: UUID="8a8fa0d6-7de0-44a5-a24d-5b97ef7a89b7" TYPE="xfs"
/dev/sda3: UUID="vRTH1r-wMfx-htsk-wQoe-fGLB-2169-nftTLt" TYPE="LVM2_member"
/dev/sdb2: UUID="1NKilr-tNwd-US1g-I1k1-1ATI-bFkg-0dtjWm" TYPE="LVM2_member"
/dev/mapper/VG65-lvroot: UUID="8d661a87-3eee-4025-9714-064774cada00" TYPE="xfs"
/dev/mapper/VG65-swap: UUID="2ab4424a-e95d-489a-96f1-c967bc6a7c0c" TYPE="swap"
e.2修改挂载文件
[root@stau63 vg65]# vim etc/fstab
#
# /etc/fstab
# Created by anaconda on Sat Dec 15 20:32:13 2018
#
# Accessible filesystems, by reference, are maintained under '/dev/disk'
# See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info
#
/dev/mapper/VG65-lvroot / xfs defaults 0 0
UUID=ccb49fe1-c127-4e1c-ae0d-996cc17a624e /boot xfs defaults 0 0
/dev/mapper/VG65-swap swap swap defaults 0 0
UUID=2018-05-07-12-53-47-00 /mnt/cdrom iso9660 defaults 0 0
f.修复grub2
f.1挂载/dev/sdb1到/boot分区
[root@stau63 ~]# mount /dev/sdb1 /boot
f.2 重新安装内核
[root@stau63 ~]# rpm -ivh /mnt/cdrom/Packages/kernel-3.10.0-862.el7.x86_64.rpm --force
Preparing... ################################# [100%]
Updating / installing...
1:kernel-3.10.0-862.el7 ################################# [100%]
f.3 grub2安装
[root@stau63 ~]# grub2-install /dev/sdb
Installing for i386-pc platform.
Installation finished. No error reported.
f.4 grub配置文件生成
[root@stau63 ~]# grub2-mkconfig -o /boot/grub2/grub.cfg
g.完成。
把63关机，65开机。可能有多个菜单可以vim /boot/grub2/grub.cfg删除多余的菜单
h. 其它
一些可以生成新UUID的方法
XFS文件系统
EXT文件系统
[root@stau63 ~]# uuidgen |xargs -i tune2fs -U {} /dev/mapper/VolGroup65-lvroot
[root@stau63 ~]# pvchange -u /dev/sda3 #为pv(/dev/sda3)随机产生一个新的uuid号
[root@stau63 ~]# vgchange -u test #为vg(test) 随机产生一个新的uuid号
修复XFS文件系统