lvm快照的创建恢复
首先，不谈理论知识，直接看过程和结果
lvs <--查看lv
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg -wi-ao---- 50.47g
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-ao---- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
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df -h <--查看挂载情况
Filesystem Size Used Avail Use% Mounted on
/dev/sda2 58G 40G 16G 72% /
tmpfs 3.9G 236K 3.9G 1% /dev/shm
/dev/sda1 194M 59M 126M 32% /boot
/dev/mapper/vg-vm3 30G 29G 16M 100% /vm/vm3
/dev/mapper/vg-vm1 50G 1.5G 46G 4% /vm/vm1 <--实验目标
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ls -lh /vm/vm1 <--查看lv内容
总用量 1.3G
-rwxr-xr-x 1 qemu qemu 100G 5月 7 18:17 os
-rw-r--r-- 1 root root 2.2K 5月 7 16:30 vm1.xml
virsh start vm1 <--启动vm（kvm），os为虚拟机的镜像img
ssh 192.168.122.100 <--远程SSH连接虚拟机（IP手动配置好）
The authenticity of host '192.168.122.100 (192.168.122.100)' can't be established.RSA key fingerprint is 18:49:fa:bc:6b:01:27:25:c5:66:f4:f8:d6:1c:b9:3c.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '192.168.122.100' (RSA) to the list of known hosts.
[email protected]'s password:
Last login: Thu May 7 18:31:11 2015
[root@localhost ~]# df -h 文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/VolGroup-lv_root 48G 728M 45G 2% /
tmpfs 246M 0 246M 0% /dev/shm
/dev/sda1 485M 32M 429M 7% /boot
/dev/mapper/VolGroup-lv_home 50G 180M 47G 1% /home
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此时回到物理机
lvcreate -n vm1_snap -s /dev/mapper/vg-vm1 -L 5G <--创建快照大小5G
Logical volume "vm1_snap" created
[root@eric ~]#
[root@eric ~]#
[root@eric ~]# lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg owi-aos--- 50.47g
vm1_snap vg swi-a-s--- 5.00g vm1 0.00
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-ao---- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
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现在可以开搞了
cd /vm/vm1 rm * rm：是否删除普通文件 "os"？y
rm：是否删除普通文件 "vm1.xml"？y
ls -l总用量 0
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回到虚拟机终端
[root@localhost ~]# ls <--哎哟，还能动
anaconda-ks.cfg install.log install.log.syslog
[root@localhost ~]# shutdown -h now
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回到物理机再次启动
virsh start vm1
错误：开始域 vm1 失败
错误：cannot open file '/vm/vm1/os': No such file or directory
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还原 <--恢复快照时，目标逻辑卷不能被挂载使用
umount /vm/vm1 lvconvert --merge /dev/vg/vm1_snap
Merging of volume vm1_snap started.
vm1: Merged: 90.0%
vm1: Merged: 100.0% Merge of snapshot into logical volume vm1 has finished. Logical volume "vm1_snap" successfully removed
这是正常情况下显示
lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg -wi-a----- 50.47g
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-a----- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
还原时同时删除快照
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验证
mount /dev/vg/vm1 /vm/vm1
ls /vm/vm1
os vm1.xml <--os出来了。
virsh start vm1
域 vm1 已开始 <--好像正常启动的样子
ssh 192.168.122.100
[email protected]'s password:
Last login: Fri May 8 10:33:28 2015
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/VolGroup-lv_root
48G 728M 45G 2% /
tmpfs 246M 0 246M 0% /dev/shm
/dev/sda1 485M 32M 429M 7% /boot
/dev/mapper/VolGroup-lv_home
50G 180M 47G 1% /home
呵呵，真的恢复了。
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恢复失败的例子
lvcreate -n vm1_snap -s /dev/vg/vm1 -L 5G
Logical volume "vm1_snap" created
lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg owi-aos--- 50.47g
vm1_snap vg swi-a-s--- 5.00g vm1 0.00
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-a----- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
rm -f /vm/vm1/os <--删除img
lvconvert --merge /dev/vg/vm1_snap <--虚拟机没关机，系统没卸载lv,直接恢复
Can't merge over open origin volume
Merging of snapshot vm1_snap will start next activation.
lvconvert --merge /dev/vg/vm1_snap
Snapshot vm1_snap is already merging
Unable to merge LV "vm1_snap" into its origin.
lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg Owi-aos--- 50.47g
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-a----- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
我去，快照没了！
virsh destroy vm1 <--关闭虚拟机
virsh start vm1
错误：开始域 vm1 失败 错误：cannot open file '/vm/vm1/os': No such file or directory
感觉完蛋了 ....
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再来
lvconvert --merge /dev/vg/vm1_snap
Snapshot vm1_snap is already merging
Unable to merge LV "vm1_snap" into its origin.
呵呵哒...
回头看之前执行后的描述，不能打开原始逻辑卷，恢复快照会在下次激活时执行
脑补了一下，尝试把lv停用（inactive）
umount /vm/vm1
lvchange -an /dev/vg/vm1 <--停用
lvdisplay /dev/vg/vm1
--- Logical volume ---
LV Path /dev/vg/vm1
LV Name vm1
VG Name vg
LV UUID ki7kEy-lxeo-We6Q-Jkgb-H0Ox-Nbsh-2Tytkq
LV Write Access read/write
LV Creation host, time eric, 2014-07-24 22:24:47 +0800
LV snapshot status source of
vm1_snap [INACTIVE]
LV Status NOT available
LV Size 50.47 GiB
Current LE 12921
Segments 1
Allocation inherit
Read ahead sectors auto
lvchange -ay /dev/vg/vm1 <--启用
lvs
LV VG Attr LSize Pool Origin Data% Move Log Cpy%Sync Convert
vm1 vg -wi-a----- 50.47g
vm2 vg -wi-a----- 30.00g
vm3 vg -wi-a----- 30.00g
vm4 vg -wi-a----- 30.00g
vm5 vg -wi-a----- 30.00g
看到木有，状态都变正常了。
[root@eric ~]# mount /dev/vg/vm1 /vm/vm1
[root@eric ~]# ls /vm/vm1
os vm1.xml <--有了
virsh start vm1
域 vm1 已开始
ssh 192.168.122.100
[email protected]'s password:
Last login: Fri May 8 11:45:03 2015
[root@localhost ~]# df -h
文件系统 容量 已用 可用 已用%% 挂载点
/dev/mapper/VolGroup-lv_root
48G 728M 45G 2% /
tmpfs 246M 0 246M 0% /dev/shm
/dev/sda1 485M 32M 429M 7% /boot
/dev/mapper/VolGroup-lv_home
50G 180M 47G 1% /home
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实验完毕